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  1. EPA Permeable Surface Research

    EPA Science Inventory

    EPA recognizes permeable surfaces as an effective post-construction infiltration-based Best Management Practice to mitigate the adverse effects of stormwater runoff. The professional user community conceptually embraces permeable surfaces as a tool for making runoff more closely...

  2. Permeability and relative permeability in rocks

    SciTech Connect

    Blair, S.C.; Berryman, J.G.

    1990-10-01

    Important features of the topology of the pore space of rocks can be usefully quantified by analyzing digitized images of rock cross sections. One approach computes statistical correlation functions using modern image processing techniques. These correlation functions contain information about porosity, specific surface area, tortuosity, formation factor, and elastic constants, as well as the fluid permeability and relative permeability. The physical basis of this approach is discussed and examples of the results for various sandstones are presented. The analysis shows that Kozeny-Carman relations and Archie's empirical laws must be modified to account for finite percolation thresholds in order to avoid unphysical behavior in the calculated relative permeabilities. 33 refs., 4 figs., 1 tab.

  3. Permeability of edible coatings.

    PubMed

    Mishra, B; Khatkar, B S; Garg, M K; Wilson, L A

    2010-01-01

    The permeabilities of water vapour, O2 and CO2 were determined for 18 coating formulations. Water vapour transmission rate ranged from 98.8 g/m(2).day (6% beeswax) to 758.0 g/m(2).day (1.5% carboxymethyl cellulose with glycerol). O2 permeability at 14 ± 1°C and 55 ± 5% RH ranged from 1.50 to 7.95 cm(3)cm cm(-2)s(-1)Pa(-1), with CO2 permeability 2 to 6 times as high. Permeability to noncondensable gases (O2 and CO2) was higher for hydrophobic (peanut oil followed by beeswax) coatings as compared to hydrophilic (whey protein concentrate and carboxymethyl cellulose).

  4. Seismic waves increase permeability.

    PubMed

    Elkhoury, Jean E; Brodsky, Emily E; Agnew, Duncan C

    2006-06-29

    Earthquakes have been observed to affect hydrological systems in a variety of ways--water well levels can change dramatically, streams can become fuller and spring discharges can increase at the time of earthquakes. Distant earthquakes may even increase the permeability in faults. Most of these hydrological observations can be explained by some form of permeability increase. Here we use the response of water well levels to solid Earth tides to measure permeability over a 20-year period. At the time of each of seven earthquakes in Southern California, we observe transient changes of up to 24 degrees in the phase of the water level response to the dilatational volumetric strain of the semidiurnal tidal components of wells at the Piñon Flat Observatory in Southern California. After the earthquakes, the phase gradually returns to the background value at a rate of less than 0.1 degrees per day. We use a model of axisymmetric flow driven by an imposed head oscillation through a single, laterally extensive, confined, homogeneous and isotropic aquifer to relate the phase response to aquifer properties. We interpret the changes in phase response as due to changes in permeability. At the time of the earthquakes, the permeability at the site increases by a factor as high as three. The permeability increase depends roughly linearly on the amplitude of seismic-wave peak ground velocity in the range of 0.21-2.1 cm s(-1). Such permeability increases are of interest to hydrologists and oil reservoir engineers as they affect fluid flow and might determine long-term evolution of hydrological and oil-bearing systems. They may also be interesting to seismologists, as the resulting pore pressure changes can affect earthquakes by changing normal stresses on faults.

  5. The Permeable Classroom.

    ERIC Educational Resources Information Center

    Sandy, Leo R.

    1998-01-01

    Discusses the concept of permeability as knowledge flow into and out of the classroom and applies it to three college courses taught by the author at Plymouth State College (New Hampshire). Experiential knowledge comes into the classroom through interviews, guest speakers, and panel presentations, and flows out through service-learning students…

  6. Scales of rock permeability

    NASA Astrophysics Data System (ADS)

    Guéguen, Y.; Gavrilenko, P.; Le Ravalec, M.

    1996-05-01

    Permeability is a transport property which is currently measured in Darcy units. Although this unit is very convenient for most purposes, its use prevents from recognizing that permeability has units of length squared. Physically, the square root of permeability can thus be seen as a characteristic length or a characteristic pore size. At the laboratory scale, the identification of this characteristic length is a good example of how experimental measurements and theoretical modelling can be integrated. Three distinct identifications are of current use, relying on three different techniques: image analysis of thin sections, mercury porosimetry and nitrogen adsorption. In each case, one or several theoretical models allow us to derive permeability from the experimental data (equivalent channel models, statistical models, effective media models, percolation and network models). Permeability varies with pressure and temperature and this is a decisive point for any extrapolation to crustal conditions. As far as pressure is concerned, most of the effect is due to cracks and a model which does not incorporate this fact will miss its goal. Temperature induced modifications can be the result of several processes: thermal cracking (due to thermal expansion mismatch and anisotropy, or to fluid pressure build up), and pressure solution are the two main ones. Experimental data on pressure and temperature effects are difficult to obtain but they are urgently needed. Finally, an important issue is: up to which point are these small scale data and models relevant when considering formations at the oil reservoir scale, or at the crust scale? At larger scales the identification of the characteristic scale is also a major goal which is examined.

  7. EPA Permeable Surface Research - Poster

    EPA Science Inventory

    EPA recognizes permeable surfaces as an effective post-construction infiltration-based Best Management Practice to mitigate the adverse effects of stormwater runoff. The professional user community conceptually embraces permeable surfaces as a tool for making runoff more closely...

  8. Liquid-permeable electrode

    DOEpatents

    Folser, George R.

    1980-01-01

    Electrodes for use in an electrolytic cell, which are liquid-permeable and have low electrical resistance and high internal surface area are provided of a rigid, porous, carbonaceous matrix having activated carbon uniformly embedded throughout. The activated carbon may be catalyzed with platinum for improved electron transfer between electrode and electrolyte. Activated carbon is mixed with a powdered thermosetting phenolic resin and compacted to the desired shape in a heated mold to melt the resin and form the green electrode. The compact is then heated to a pyrolyzing temperature to carbonize and volatilize the resin, forming a rigid, porous structure. The permeable structure and high internal surface area are useful in electrolytic cells where it is necessary to continuously remove the products of the electrochemical reaction.

  9. [Venoruton and capillary permeability].

    PubMed

    Cesarone, M R; Laurora, G; Gabini, M; Errichi, B M; Candiani, C; Belcaro, G

    1989-05-01

    A new system to evaluate capillary permeability, the vacuum suction chamber (VSC) device, was used to assess the effects of Venoruton in patients with venous hypertension. A temporary, superficial skin lesion (wheal) was produced with the VSC device by negative pressure (30 mmHg) applied for 10 minutes on the internal, perimalleolar region. Wheals disappear in less than 60 minutes in normals while in patients with venous hypertension the wheal is more persistent, requiring a significantly longer time to disappear. This new technique was used in association with laser-Doppler flowmetry to evaluate the efficacy of Venoruton (1000 mgs t.i.d.) administered for 2 weeks on venous hypertension. Results indicate a positive effect of Venoruton in reducing the abnormally increased capillary permeability in venous hypertension and are proportional to the changes observed in signs and symptoms after treatment.

  10. Stainless Steel Permeability

    SciTech Connect

    Buchenauer, Dean A.; Karnesky, Richard A.

    2015-09-01

    An understanding of the behavior of hydrogen isotopes in materials is critical to predicting tritium transport in structural metals (at high pressure), estimating tritium losses during production (fission environment), and predicting in-vessel inventory for future fusion devices (plasma driven permeation). Current models often assume equilibrium diffusivity and solubility for a class of materials (e.g. stainless steels or aluminum alloys), neglecting trapping effects or, at best, considering a single population of trapping sites. Permeation and trapping studies of the particular castings and forgings enable greater confidence and reduced margins in the models. For FY15, we have continued our investigation of the role of ferrite in permeation for steels of interest to GTS, through measurements of the duplex steel 2507. We also initiated an investigation of the permeability in work hardened materials, to follow up on earlier observations of unusual permeability in a particular region of 304L forgings. Samples were prepared and characterized for ferrite content and coated with palladium to prevent oxidation. Issues with the poor reproducibility of measurements at low permeability were overcome, although the techniques in use are tedious. Funding through TPBAR and GTS were secured for a research grade quadrupole mass spectrometer (QMS) and replacement turbo pumps, which should improve the fidelity and throughput of measurements in FY16.

  11. Relative permeability through fractures

    SciTech Connect

    Diomampo, Gracel, P.

    2001-08-01

    The mechanism of two-phase flow through fractures is of importance in understanding many geologic processes. Currently, two-phase flow through fractures is still poorly understood. In this study, nitrogen-water experiments were done on both smooth and rough parallel plates to determine the governing flow mechanism for fractures and the appropriate methodology for data analysis. The experiments were done using a glass plate to allow visualization of flow. Digital video recording allowed instantaneous measurement of pressure, flow rate and saturation. Saturation was computed using image analysis techniques. The experiments showed that gas and liquid phases flow through fractures in nonuniform separate channels. The localized channels change with time as each phase path undergoes continues breaking and reforming due to invasion of the other phase. The stability of the phase paths is dependent on liquid and gas flow rate ratio. This mechanism holds true for over a range of saturation for both smooth and rough fractures. In imbibition for rough-walled fractures, another mechanism similar to wave-like flow in pipes was also observed. The data from the experiments were analyzed using Darcy's law and using the concept of friction factor and equivalent Reynold's number for two-phase flow. For both smooth- and rough-walled fractures a clear relationship between relative permeability and saturation was seen. The calculated relative permeability curves follow Corey-type behavior and can be modeled using Honarpour expressions. The sum of the relative permeabilities is not equal one, indicating phase interference. The equivalent homogeneous single-phase approach did not give satisfactory representation of flow through fractures. The graphs of experimentally derived friction factor with the modified Reynolds number do not reveal a distinctive linear relationship.

  12. Bovine Colostrum Supplementation During Running Training Increases Intestinal Permeability

    PubMed Central

    Buckley, Jonathan D.; Butler, Ross N.; Southcott, Emma; Brinkworth, Grant D.

    2009-01-01

    Endurance exercise training can increase intestinal permeability which may contribute to the development of gastrointestinal symptoms in some athletes. Bovine colostrum (BC) supplementation reduces intestinal permeability induced by non-steroidal anti-inflammatory drugs. This study aimed to determine whether BC could also reduce intestinal permeability induced by endurance exercise. Thirty healthy adult males (25.0 ± 4.7 yr; mean ± SD) completed eight weeks of running three times per week for 45 minutes at their lactate threshold while consuming 60 g/day of BC, whey protein (WP) or control (CON). Intestinal permeability was assessed at baseline and after eight weeks by measuring the ratio of urinary lactulose (L) and rhamnose (R) excretion. After eight weeks the L/R ratio increased significantly more in volunteers consuming BC (251 ± 140%) compared with WP (21 ± 35%, P < 0.05) and CON (−7 ± 13%, P < 0.02). The increase in intestinal permeability with BC may have been due to BC inducing greater leakiness of tight junctions between enterocytes or by increasing macromolecular transport as it does in neonatal gut. Further research should investigate the potential for BC to increase intestinal macromolecular transport in adults. PMID:22253980

  13. Impacts « multi-échelle » d'un échange (Mg,Ca) Pb et ses conséquences sur l'augmentation de la perméabilité d'une bentoniteMultiscale impacts of a (Mg,Ca) Pb exchange on the permeability increase of a bentonite

    NASA Astrophysics Data System (ADS)

    Jozja, Nevila; Baillif, Patrick; Touray, Jean-Claude; Pons, Charles-Henri; Muller, Fabrice; Burgevin, Carole

    2003-09-01

    The article addresses the structural effects of solutions of lead nitrate on a suspended or compacted bentonite. A permeability increase is observed on compacted clay. Investigating the composition of output solution, using X-Rays Diffusion at Small Angles and Scanning Electron Microscopy, this permeability increase is explained from structural variations at nanometric (reduction of particle size) and micrometric scales (microfissuration of aggregates). To cite this article: N. Jozja et al., C. R. Geoscience 335 (2003).

  14. Electrokinetic effects and fluid permeability

    NASA Astrophysics Data System (ADS)

    G. Berryman, James

    2003-10-01

    Fluid permeability of porous media depends mainly on connectivity of the pore space and two physical parameters: porosity and a pertinent length-scale parameter. Electrical imaging methods typically establish connectivity and directly measure electrical conductivity, which can then often be related to porosity by Archie's law. When electrical phase measurements are made in addition to the amplitude measurements, information about the pertinent length scale can then be obtained. Since fluid permeability controls the ability to flush unwanted fluid contaminants from the subsurface, inexpensive maps of permeability could improve planning strategies for remediation efforts. Detailed knowledge of fluid permeability is also important for oil field exploitation, where knowledge of permeability distribution in three dimensions is a common requirement for petroleum reservoir simulation and analysis, as well as for estimates on the economics of recovery.

  15. Permeable membrane experiment

    NASA Technical Reports Server (NTRS)

    Slavin, Thomas J.; Cao, Tuan Q.; Kliss, Mark H.

    1993-01-01

    The purpose of the Permeable Membrane Experiment is to gather flight data on three areas of membrane performance that are influenced by the presence of gravity. These areas are: (1) Liquid/gas phase separation, (2) gas bubble interference with diffusion through porous membranes and (3) wetting characteristics of hydrophilic membrane surfaces. These data are important in understaning the behavior of membrane/liquid/gas interfaces where surface tension forces predominate. The data will be compared with 1-g data already obtained and with predicted micrograviity behavior. The data will be used to develop designs for phase separation and plant nutrient delivery systems and will be available to the life support community for use in developing technologies which employ membranes. A conceptual design has been developed to conduct three membrane experiments, in sequence, aboard a single Complex Autonomous Payload (CAP) carrier to be carried in the Shuttle Orbiter payload bay. One experiment is conducted for each of the three membrane performance areas under study. These experiments are discussed in this paper.

  16. Relative Permeability of Fractured Rock

    SciTech Connect

    Mark D. Habana

    2002-06-30

    Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

  17. Geothermal Permeability Enhancement - Final Report

    SciTech Connect

    Joe Beall; Mark Walters

    2009-06-30

    The overall objective is to apply known permeability enhancement techniques to reduce the number of wells needed and demonstrate the applicability of the techniques to other undeveloped or under-developed fields. The Enhanced Geothermal System (EGS) concept presented in this project enhances energy extraction from reduced permeability zones in the super-heated, vapor-dominated Aidlin Field of the The Geysers geothermal reservoir. Numerous geothermal reservoirs worldwide, over a wide temperature range, contain zones of low permeability which limit the development potential and the efficient recovery of heat from these reservoirs. Low permeability results from poorly connected fractures or the lack of fractures. The Enhanced Geothermal System concept presented here expands these technologies by applying and evaluating them in a systematic, integrated program.

  18. Permeability of soils in Mississippi

    USGS Publications Warehouse

    O'Hara, Charles G.

    1994-01-01

    The permeability of soils in Mississippi was determined and mapped using a geographic information system (GIS). Soil permeabilities in Mississippi were determined to range in value from nearly 0.0 to values exceeding 5.0 inches per hour. The U.S. Soil Conservation Service's State Soil Geographic Data Base (STATSGO) was used as the primary source of data for the determination of area-weighted soil permeability. STATSGO provides soil layer properties that are spatially referenced to mapped areas. These mapped areas are referred to as polygons in the GIS. The polygons arc boundaries of soils mapped as a group and are given unique Map Unit Identifiers (MUIDs). The data describing the physical characteristics of the soils within each polygon are stored in a tabular data base format and are referred to as attributes. The U.S. Soil Conservation Service developed STATSGO to be primarily used as a guide for regional resource planning, management, and monitoring. STATSGO was designed so that soil information could be extracted from properties tables at the layer level, combined by component, and statistically expanded to cover the entire map unit. The results of this study provide a mapped value for permeability which is representative of the vertical permeability of soils in that area. The resultant permeability map provides a representative vertical soil permeability for a given area sufficient for county, multi- county, and area planning, and will be used as the soil permeability data component in the evaluation of the susceptibility of major aquifers to contami- nation in Mississippi.

  19. Permeability Asymmetry in Composite Porous Ceramic Membranes

    NASA Astrophysics Data System (ADS)

    Kurcharov, I. M.; Laguntsov, N. I.; Uvarov, V. I.; Kurchatova, O. V.

    The results from the investigation of transport characteristics and gas transport asymmetry in bilayer composite membranes are submitted. These membranes are produced by SHS method. Asymmetric effect and hysteresis of permeability in nanoporous membranes are detected. It's shown, that permeability ratio (asymmetry value of permeability) increases up to several times. The asymmetry of permeability usually decreases monotonically with the pressure decrease.

  20. Permeability extraction: A sonic log inversion

    SciTech Connect

    Akbar, N.; Kim, J.J.

    1994-12-31

    In this paper the authors provide the missing important link between permeability and acoustic velocities by generating a permeability-dependent synthetic sonic log in a carbonate reservoir. The computations are based on Akbar`s theory that relates wave velocity to frequency, rock properties (e.g., lithology, permeability, and porosity), and fluid saturation and properties (viscosity, density, and compressibility). An inverted analytical expression of the theory is used to extract permeability from sonic velocity. The synthetic sonic and the computed permeability are compared with the observed sonic log and with plug permeability, respectively. The results demonstrate, as predicted by theory, that permeability can be related directly to acoustic velocities.

  1. Permeability of stylolite-bearing chalk

    SciTech Connect

    Lind, I.; Nykjaer, O.; Priisholm, S. ); Springer, N.

    1994-11-01

    Permeabilities were measured on core plugs from stylolite-bearing chalk of the Gorm field in the Danish North Sea. Air and liquid permeabilities were measured in directions parallel to and perpendicular to the stylolite surface. Permeability was measured with sleeve pressure equal to in-situ reservoir stress. Permeabilities of plugs with stylolites but without stylolite-associated fractures were equal in the two directions. The permeability is equal to the matrix permeability of non-stylolite-bearing chalk. In contrast, when fractures were associated with the stylolites, permeability was enhanced. The enhancement was most significant in the horizontal direction parallel to the stylolites.

  2. Paranodal permeability in `myelin mutants'

    PubMed Central

    Shroff, S.; Mierzwa, A.; Scherer, S.S.; Peles, E.; Arevalo, J.C.; Chao, M.V.; Rosenbluth, J.

    2011-01-01

    Fluorescent dextran tracers of varying sizes have been used to assess paranodal permeability in myelinated sciatic nerve fibers from control and three `myelin mutant' mice, Caspr-null, cst-null and shaking. We demonstrate that in all of these the paranode is permeable to small tracers (3kDa, 10kDa), which penetrate most fibers, and to larger tracers (40kDa, 70kDa), which penetrate far fewer fibers and move shorter distances over longer periods of time. Despite gross diminution in transverse bands in the Caspr-null and cst-null mice, the permeability of their paranodal junctions is equivalent to that in controls. Thus, deficiency of transverse bands in these mutants does not increase the permeability of their paranodal junctions to the dextrans we used, moving from the perinodal space through the paranode to the internodal periaxonal space. In addition, we show that the shaking mice, which have thinner myelin and shorter paranodes, show increased permeability to the same tracers despite the presence of transverse bands. We conclude that the extent of penetration of these tracers does not depend on the presence or absence of transverse bands but does depend on the length of the paranode and, in turn, on the length of `pathway 3', the helical extracellular pathway that passes through the paranode parallel to the lateral edge of the myelin sheath. PMID:21618613

  3. Paranodal permeability in "myelin mutants".

    PubMed

    Shroff, Seema; Mierzwa, Amanda; Scherer, Steven S; Peles, Elior; Arevalo, Juan C; Chao, Moses V; Rosenbluth, Jack

    2011-10-01

    Fluorescent dextran tracers of varying sizes have been used to assess paranodal permeability in myelinated sciatic nerve fibers from control and three "myelin mutant" mice, Caspr-null, cst-null, and shaking. We demonstrate that in all of these the paranode is permeable to small tracers (3 kDa and 10 kDa), which penetrate most fibers, and to larger tracers (40 kDa and 70 kDa), which penetrate far fewer fibers and move shorter distances over longer periods of time. Despite gross diminution in transverse bands (TBs) in the Caspr-null and cst-null mice, the permeability of their paranodal junctions is equivalent to that in controls. Thus, deficiency of TBs in these mutants does not increase the permeability of their paranodal junctions to the dextrans we used, moving from the perinodal space through the paranode to the internodal periaxonal space. In addition, we show that the shaking mice, which have thinner myelin and shorter paranodes, show increased permeability to the same tracers despite the presence of TBs. We conclude that the extent of penetration of these tracers does not depend on the presence or absence of TBs but does depend on the length of the paranode and, in turn, on the length of "pathway 3," the helical extracellular pathway that passes through the paranode parallel to the lateral edge of the myelin sheath. PMID:21618613

  4. Measuring Vascular Permeability In Vivo.

    PubMed

    Meijer, Eelco F J; Baish, James W; Padera, Timothy P; Fukumura, Dai

    2016-01-01

    Over the past decades, in vivo vascular permeability measurements have provided significant insight into vascular functions in physiological and pathophysiological conditions such as the response to pro- and anti-angiogenic signaling, abnormality of tumor vasculature and its normalization, and delivery and efficacy of therapeutic agents. Different approaches for vascular permeability measurements have been established. Here, we describe and discuss a conventional 2D imaging method to measure vascular permeability, which was originally documented by Gerlowski and Jain in 1986 (Microvasc Res 31:288-305, 1986) and further developed by Yuan et al. in the early 1990s (Microvasc Res 45:269-289, 1993; Cancer Res 54:352-3356, 1994), and our recently developed 3D imaging method, which advances the approach originally described by Brown et al. in 2001 (Nat Med 7:864-868, 2001). PMID:27581015

  5. Permeability enhancement by shock cooling

    NASA Astrophysics Data System (ADS)

    Griffiths, Luke; Heap, Michael; Reuschlé, Thierry; Baud, Patrick; Schmittbuhl, Jean

    2015-04-01

    The permeability of an efficient reservoir, e.g. a geothermal reservoir, should be sufficient to permit the circulation of fluids. Generally speaking, permeability decreases over the life cycle of the geothermal system. As a result, is usually necessary to artificially maintain and enhance the natural permeability of these systems. One of the methods of enhancement -- studied here -- is thermal stimulation (injecting cold water at low pressure). This goal of this method is to encourage new thermal cracks within the reservoir host rocks, thereby increasing reservoir permeability. To investigate the development of thermal microcracking in the laboratory we selected two granites: a fine-grained (Garibaldi Grey granite, grain size = 0.5 mm) and a course-grained granite (Lanhelin granite, grain size = 2 mm). Both granites have an initial porosity of about 1%. Our samples were heated to a range of temperatures (100-1000 °C) and were either cooled slowly (1 °C/min) or shock cooled (100 °C/s). A systematic microstructural (2D crack area density, using standard stereological techniques, and 3D BET specific surface area measurements) and rock physical property (porosity, P-wave velocity, uniaxial compressive strength, and permeability) analysis was undertaken to understand the influence of slow and shock cooling on our reservoir granites. Microstructurally, we observe that the 2D crack surface area per unit volume and the specific surface area increase as a result of thermal stressing, and, for the same maximum temperature, crack surface area is higher in the shock cooled samples. This observation is echoed by our rock physical property measurements: we see greater changes for the shock cooled samples. We can conclude that shock cooling is an extremely efficient method of generating thermal microcracks and modifying rock physical properties. Our study highlights that thermal treatments are likely to be an efficient method for the "matrix" permeability enhancement of

  6. High membrane permeability for melatonin.

    PubMed

    Yu, Haijie; Dickson, Eamonn J; Jung, Seung-Ryoung; Koh, Duk-Su; Hille, Bertil

    2016-01-01

    The pineal gland, an endocrine organ in the brain, synthesizes and secretes the circulating night hormone melatonin throughout the night. The literature states that this hormone is secreted by simple diffusion across the pinealocyte plasma membrane, but a direct quantitative measurement of membrane permeability has not been made. Experiments were designed to compare the cell membrane permeability to three indoleamines: melatonin and its precursors N-acetylserotonin (NAS) and serotonin (5-HT). The three experimental approaches were (1) to measure the concentration of effluxing indoleamines amperometrically in the bath while cells were being dialyzed internally by a patch pipette, (2) to measure the rise of intracellular indoleamine fluorescence as the compound was perfused in the bath, and (3) to measure the rate of quenching of intracellular fura-2 dye fluorescence as indoleamines were perfused in the bath. These measures showed that permeabilities of melatonin and NAS are high (both are uncharged molecules), whereas that for 5-HT (mostly charged) is much lower. Comparisons were made with predictions of solubility-diffusion theory and compounds of known permeability, and a diffusion model was made to simulate all of the measurements. In short, extracellular melatonin equilibrates with the cytoplasm in 3.5 s, has a membrane permeability of ∼1.7 µm/s, and could not be retained in secretory vesicles. Thus, it and NAS will be "secreted" from pineal cells by membrane diffusion. Circumstances are suggested when 5-HT and possibly catecholamines may also appear in the extracellular space passively by membrane diffusion. PMID:26712850

  7. High membrane permeability for melatonin

    PubMed Central

    Yu, Haijie; Dickson, Eamonn J.; Jung, Seung-Ryoung; Koh, Duk-Su

    2016-01-01

    The pineal gland, an endocrine organ in the brain, synthesizes and secretes the circulating night hormone melatonin throughout the night. The literature states that this hormone is secreted by simple diffusion across the pinealocyte plasma membrane, but a direct quantitative measurement of membrane permeability has not been made. Experiments were designed to compare the cell membrane permeability to three indoleamines: melatonin and its precursors N-acetylserotonin (NAS) and serotonin (5-HT). The three experimental approaches were (1) to measure the concentration of effluxing indoleamines amperometrically in the bath while cells were being dialyzed internally by a patch pipette, (2) to measure the rise of intracellular indoleamine fluorescence as the compound was perfused in the bath, and (3) to measure the rate of quenching of intracellular fura-2 dye fluorescence as indoleamines were perfused in the bath. These measures showed that permeabilities of melatonin and NAS are high (both are uncharged molecules), whereas that for 5-HT (mostly charged) is much lower. Comparisons were made with predictions of solubility-diffusion theory and compounds of known permeability, and a diffusion model was made to simulate all of the measurements. In short, extracellular melatonin equilibrates with the cytoplasm in 3.5 s, has a membrane permeability of ∼1.7 µm/s, and could not be retained in secretory vesicles. Thus, it and NAS will be “secreted” from pineal cells by membrane diffusion. Circumstances are suggested when 5-HT and possibly catecholamines may also appear in the extracellular space passively by membrane diffusion. PMID:26712850

  8. Permeable Pavement Research - Edison, New Jersey

    EPA Science Inventory

    This presentation provides the background and summary of results collected at the permeable pavement parking lot monitored at the EPA facility in Edison, NJ. This parking lot is surfaced with permeable interlocking concrete pavers (PICP), pervious concrete, and porous asphalt. ...

  9. Quantifying Evaporation in a Permeable Pavement System

    EPA Science Inventory

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. Th...

  10. Vapor-liquid phase separator permeability results

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Frederking, T. H. K.

    1981-01-01

    Continued studies are described in the area of vapor-liquid phase separator work with emphasis on permeabilities of porous sintered plugs (stainless steel, nominal pore size 2 micrometer). The temperature dependence of the permeability has been evaluated in classical fluid using He-4 gas at atmospheric pressure and in He-2 on the basis of a modified, thermosmotic permeability of the normal fluid.

  11. Structure/Permeability Relationships Of Polyimide Membranes

    NASA Technical Reports Server (NTRS)

    St. Clair, A. K.; Yamamoto, H.; Mi, Y.; Stern, S. A.

    1995-01-01

    Report describes experimental study of permeabilities, by each of five gases, of membranes made of four different polyimides. Conducted to gain understanding of effects of molecular structures of membranes on permeabilities and to assess potential for exploitation of selective permeability in gas-separation processes. Gases used: H2, O2, N2, CO2, and CH4.

  12. Novel additives to retard permeable flow

    SciTech Connect

    Golombok, Michael; Crane, Carel; Ineke, Erik; Welling, Marco; Harris, Jon

    2008-09-15

    Low concentrations of surfactant and cosolute in water, can selectively retard permeable flow in high permeability rocks compared to low permeability ones. This represents a way forward for more efficient areal sweep efficiency when water flooding a reservoir during improved oil recovery. (author)

  13. Hydrofacies In Sandstones. Evidence For Feedback Between Sandstone Lithofacies and Permeability Development

    NASA Astrophysics Data System (ADS)

    Bloomfield, J. P.; Newell, A.; Moreau, M.

    In order to enhance our ability to develop effective numerical models of flow and con- taminant transport in the Permo-Triassic sandstone aquifer of the UK, relationships between lithofacies, rock mass characteristics (such as porosity and pore-throat size distribution), and permeability have been investigated through a series of case studies. Flow in the Permo-Triassic sandstones is primarily through the matrix. Permeability distribution is principally a function of the pore-throat size distribution and there is a relatively weak correlation with primary sedimentary lithofacies. It is observed that matrix permeability data broadly fall into two, discontinuous, sub-populations above and below about 1 mD. It is proposed that modification of primary sedimentary litho- facies by circulation of groundwater is the main control on the development of these two permeability sub-populations or hydrofacies. Identification of these two hydrofa- cies has significant implications for numerical modelling of the sandstones.

  14. Permeability relation for periodic structures.

    PubMed

    Dunn, K J; LaTorraca, G A; Bergman, D J

    1998-01-01

    The permeability relation for periodic porous media is studied with respect to other petrophysical parameters such as formation factor, porosity, surface-to-volume ratio, and nuclear magnetic resonance (NMR) relaxation time. All these quantities were computed for periodic structures of simple, body-centered, and face-centered cubic arrays of touching and overlapping spheres. The formation factors were calculated by using a method which is based on a Fourier-space representation of an integral equation for the electric potential in a two-component composite. The nuclear magnetic resonance relaxation time for the case where surface-enchanced relaxation plays a dominant role is known to be V P/rho S (VP is the pore volume, S is the pore surface, is the surface relaxation strength) when rho is not too large. Previously calculated permeabilities for these structures from the literature were used for correlation studies with other petrophysical parameters. Various correlation schemes among these quantities, such as k = aTbFc, and k = aTb phi c, were investigated, where k is permeability, T is the NMR relaxation time, phi is the porosity, and F is the formation factor. PMID:9803908

  15. Permeability equipment for porous friction surfaces

    NASA Astrophysics Data System (ADS)

    Standiford, D. L.; Graul, R. A.; Lenke, L. R.

    1985-04-01

    Hydroplaning is the loss of traction between tires and pavement due to the presence of a layer of water. This loss of traction can result in loss of vehicle control. A porous friction surface (PFS) applied over an existing pavement permits the water to drain laterally and vertically away from the tire path, effectively lowering hydroplaning potential. Equipment used to measure pavement drainage (permeability) is discussed with respect to usage on porous friction surface. Background information on hydroplaning, flow theory, and PFS field performance as they are affected by permeability are also presented. Two dynamic test devices and four static devices are considered for measuring PFS permeability. Permeability tests are recommended to measure PFS permeability for maintenance purposes and construction control. Dynamic devices cited could possibly estimate hydroplaning potential; further research must be done to determine this. Permeability devices cannot be used to accurately estimate friction of a pavement surface, however, decreased permeability of a pavement infers a decrease in friction.

  16. Steam-water relative permeability

    SciTech Connect

    Ambusso, W.; Satik, C.; Home, R.N.

    1997-12-31

    A set of relative permeability relations for simultaneous flow of steam and water in porous media have been measured in steady state experiments conducted under the conditions that eliminate most errors associated with saturation and pressure measurements. These relations show that the relative permeabilities for steam-water flow in porous media vary approximately linearly with saturation. This departure from the nitrogen/water behavior indicates that there are fundamental differences between steam/water and nitrogen/water flows. The saturations in these experiments were measured by using a high resolution X-ray computer tomography (CT) scanner. In addition the pressure gradients were obtained from the measurements of liquid phase pressure over the portions with flat saturation profiles. These two aspects constitute a major improvement in the experimental method compared to those used in the past. Comparison of the saturation profiles measured by the X-ray CT scanner during the experiments shows a good agreement with those predicted by numerical simulations. To obtain results that are applicable to general flow of steam and water in porous media similar experiments will be conducted at higher temperature and with porous rocks of different wetting characteristics and porosity distribution.

  17. Accurate determination of characteristic relative permeability curves

    NASA Astrophysics Data System (ADS)

    Krause, Michael H.; Benson, Sally M.

    2015-09-01

    A recently developed technique to accurately characterize sub-core scale heterogeneity is applied to investigate the factors responsible for flowrate-dependent effective relative permeability curves measured on core samples in the laboratory. The dependency of laboratory measured relative permeability on flowrate has long been both supported and challenged by a number of investigators. Studies have shown that this apparent flowrate dependency is a result of both sub-core scale heterogeneity and outlet boundary effects. However this has only been demonstrated numerically for highly simplified models of porous media. In this paper, flowrate dependency of effective relative permeability is demonstrated using two rock cores, a Berea Sandstone and a heterogeneous sandstone from the Otway Basin Pilot Project in Australia. Numerical simulations of steady-state coreflooding experiments are conducted at a number of injection rates using a single set of input characteristic relative permeability curves. Effective relative permeability is then calculated from the simulation data using standard interpretation methods for calculating relative permeability from steady-state tests. Results show that simplified approaches may be used to determine flowrate-independent characteristic relative permeability provided flow rate is sufficiently high, and the core heterogeneity is relatively low. It is also shown that characteristic relative permeability can be determined at any typical flowrate, and even for geologically complex models, when using accurate three-dimensional models.

  18. Influence of fiber packing structure on permeability

    NASA Technical Reports Server (NTRS)

    Cai, Zhong; Berdichevsky, Alexander L.

    1993-01-01

    The study on the permeability of an aligned fiber bundle is the key building block in modeling the permeability of advanced woven and braided preforms. Available results on the permeability of fiber bundles in the literature show that a substantial difference exists between numerical and analytical calculations on idealized fiber packing structures, such as square and hexagonal packing, and experimental measurements on practical fiber bundles. The present study focuses on the variation of the permeability of a fiber bundle under practical process conditions. Fiber bundles are considered as containing openings and fiber clusters within the bundle. Numerical simulations on the influence of various openings on the permeability were conducted. Idealized packing structures are used, but with introduced openings distributed in different patterns. Both longitudinal and transverse flow are considered. The results show that openings within the fiber bundle have substantial effect on the permeability. In the longitudinal flow case, the openings become the dominant flow path. In the transverse flow case, the fiber clusters reduce the gap sizes among fibers. Therefore the permeability is greatly influenced by these openings and clusters, respectively. In addition to the porosity or fiber volume fraction, which is commonly used in the permeability expression, another fiber bundle status parameter, the ultimate fiber volume fraction, is introduced to capture the disturbance within a fiber bundle.

  19. A method of determination of permeability

    SciTech Connect

    Kuznetsov, S.V.; Trofimov, V.A.

    2007-11-15

    A method is proposed for determining permeability of coals under conditions of steady-state deformation and stationary filtration mode by employing a reference core made of gas-non-sorbing material with a known permeability. The approach has been developed to assess the time of transition to the stable filtration.

  20. Pressure sensitivity of low permeability sandstones

    USGS Publications Warehouse

    Kilmer, N.H.; Morrow, N.R.; Pitman, J.K.

    1987-01-01

    Detailed core analysis has been carried out on 32 tight sandstones with permeabilities ranging over four orders of magnitude (0.0002 to 4.8 mD at 5000 psi confining pressure). Relationships between gas permeability and net confining pressure were measured for cycles of loading and unloading. For some samples, permeabilities were measured both along and across bedding planes. Large variations in stress sensitivity of permeability were observed from one sample to another. The ratio of permeability at a nominal confining pressure of 500 psi to that at 5000 psi was used to define a stress sensitivity ratio. For a given sample, confining pressure vs permeability followed a linear log-log relationship, the slope of which provided an index of pressure sensitivity. This index, as obtained for first unloading data, was used in testing relationships between stress sensitivity and other measured rock properties. Pressure sensitivity tended to increase with increase in carbonate content and depth, and with decrease in porosity, permeability and sodium feldspar. However, scatter in these relationships increased as permeability decreased. Tests for correlations between pressure sensitivity and various linear combinations of variables are reported. Details of pore structure related to diagenetic changes appears to be of much greater significance to pressure sensitivity than mineral composition. ?? 1987.

  1. Effect of Dead Algae on Soil Permeability

    SciTech Connect

    Harvey, R.S.

    2003-02-21

    Since existing basins support heavy growths of unicellular green algae which may be killed by temperature variation or by inadvertent pH changes in waste and then deposited on the basin floor, information on the effects of dead algae on soil permeability was needed. This study was designed to show the effects of successive algal kills on the permeability of laboratory soil columns.

  2. Compact rock material gas permeability properties

    NASA Astrophysics Data System (ADS)

    Wang, Huanling; Xu, Weiya; Zuo, Jing

    2014-09-01

    Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO2, shale gas, and radioactive waste because they have extremely low permeabilities and high mechanical strengths. Using the inert gas argon as the fluid medium, the stress-dependent permeability and porosity of monzonitic granite and granite gneiss from an underground oil storage depot were measured using a permeability and porosity measurement system. Based on the test results, models for describing the relationships among the permeability, porosity, and confining pressure of rock specimens were analyzed and are discussed. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability; for the monzonitic granite and granite gneiss (for monzonitic granite (A-2), the initial porosity is approximately 4.05%, and the permeability is approximately 10-19 m2; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10-17 m2; and the porosity-sensitivity exponents that link porosity and permeability are 0.98 and 3.11, respectively). Compared with moderate-porosity and high-porosity rocks, for which φ > 15%, low-porosity rock permeability has a relatively lower sensitivity to stress, but the porosity is more sensitive to stress, and different types of rocks show similar trends. From the test results, it can be inferred that the test rock specimens' permeability evolution is related to the relative particle movements and microcrack closure.

  3. Changes in Permeability Produced By Distant Earthquakes

    NASA Astrophysics Data System (ADS)

    Manga, M.; Wang, C. Y.; Shi, Z.

    2014-12-01

    Oscillations in stress, such as those created by earthquakes, can increase permeability and fluid mobility in geologic media. In natural systems, strain amplitudes as small as 10-6 can increase discharge in streams and springs, change the water level of wells, and enhance production from petroleum reservoirs. Enhanced permeability typically recovers to pre-stimulated values over a period of months to years. This presentation will review some of the observations that indicate that dynamic stresses produced by seismic waves change permeability. We use the response of a set of wells distributed throughout China to multiple large earthquakes to probe the relationship between earthquake-generated stresses and water-level changes in wells. We find that dynamic stresses dominate the responses at distances more than 1 fault length from the earthquake and that permeability changes may explain the water level changes. Regions with high deformation rates are most sensitive to seismic waves. We also consider the response of a large alluvial fan in Taiwan to the 1999 M7.5 Chi-Chi earthquake where there were sustained changes in groundwater temperature after the earthquake. Using groundwater flow models, we infer that permeability increased by an order of magnitude over horizontal scales of tens of km, and vertical scales of several km. Permeability returned to the pre-earthquake value over many months. As much as half the total transport in the fan occurs during the short time periods with enhanced permeability.

  4. Fluid permeability of deformable fracture networks

    SciTech Connect

    Brown, S.R.; Bruhn, R.L.

    1997-04-01

    The authors consider the problem of defining the fracture permeability tensor for each grid lock in a rock mass from maps of natural fractures. For this purpose they implement a statistical model of cracked rock due to M. Oda [1985], where the permeability tensor is related to the crack geometry via a volume average of the contribution from each crack in the population. In this model tectonic stress is implicitly coupled to fluid flow through an assumed relationship between crack aperture and normal stress across the crack. The authors have included the following enhancements to the basic model: (1) a realistic model of crack closure under stress has been added along with the provision to apply tectonic stresses to the fracture system in any orientation, the application of stress results in fracture closure and consequently a reduction in permeability; (2) the fracture permeability can be superimposed onto an arbitrary anisotropic matrix permeability; (3) the fracture surfaces are allowed to slide under the application of shear stress, causing fractures to dilate and result in a permeability increase. Through an example, the authors demonstrate that significant changes in permeability magnitudes and orientations are possible when tectonic stress is applied to a fracture system.

  5. Using magnetic permeability bits to store information

    NASA Astrophysics Data System (ADS)

    Timmerwilke, John; Petrie, J. R.; Wieland, K. A.; Mencia, Raymond; Liou, Sy-Hwang; Cress, C. D.; Newburgh, G. A.; Edelstein, A. S.

    2015-10-01

    Steps are described in the development of a new magnetic memory technology, based on states with different magnetic permeability, with the capability to reliably store large amounts of information in a high-density form for decades. The advantages of using the permeability to store information include an insensitivity to accidental exposure to magnetic fields or temperature changes, both of which are known to corrupt memory approaches that rely on remanent magnetization. The high permeability media investigated consists of either films of Metglas 2826 MB (Fe40Ni38Mo4B18) or bilayers of permalloy (Ni78Fe22)/Cu. Regions of films of the high permeability media were converted thermally to low permeability regions by laser or ohmic heating. The permeability of the bits was read by detecting changes of an external 32 Oe probe field using a magnetic tunnel junction 10 μm away from the media. Metglas bits were written with 100 μs laser pulses and arrays of 300 nm diameter bits were read. The high and low permeability bits written using bilayers of permalloy/Cu are not affected by 10 Mrad(Si) of gamma radiation from a 60Co source. An economical route for writing and reading bits as small at 20 nm using a variation of heat assisted magnetic recording is discussed.

  6. Permeability Barrier Generation in the Martian Lithosphere

    NASA Astrophysics Data System (ADS)

    Schools, Joe; Montési, Laurent

    2015-11-01

    Permeability barriers develop when a magma produced in the interior of a planet rises into the cooler lithosphere and crystallizes more rapidly than the lithosphere can deform (Sparks and Parmentier, 1991). Crystallization products may then clog the porous network in which melt is propagating, reducing the permeability to almost zero, i.e., forming a permeability barrier. Subsequent melts cannot cross the barrier. Permeability barriers have been useful to explain variations in crustal thickness at mid-ocean ridges on Earth (Magde et al., 1997; Hebert and Montési, 2011; Montési et al., 2011). We explore here under what conditions permeability barriers may form on Mars.We use the MELTS thermodynamic calculator (Ghiorso and Sack, 1995; Ghiorso et al., 2002; Asimow et al., 2004) in conjunction with estimated Martian mantle compositions (Morgan and Anders, 1979; Wänke and Dreibus, 1994; Lodders and Fegley, 1997; Sanloup et al., 1999; Taylor 2013) to model the formation of permeability barriers in the lithosphere of Mars. In order to represent potential past and present conditions of Mars, we vary the lithospheric thickness, mantle potential temperature (heat flux), oxygen fugacity, and water content.Our results show that permeability layers can develop in the thermal boundary layer of the simulated Martian lithosphere if the mantle potential temperature is higher than ~1500°C. The various Martian mantle compositions yield barriers in the same locations, under matching variable conditions. There is no significant difference in barrier location over the range of accepted Martian oxygen fugacity values. Water content is the most significant influence on barrier development as it reduces the temperature of crystallization, allowing melt to rise further into the lithosphere. Our lower temperature and thicker lithosphere model runs, which are likely the most similar to modern Mars, show no permeability barrier generation. Losing the possibility of having a permeability

  7. Gas Permeable Chemochromic Compositions for Hydrogen Sensing

    NASA Technical Reports Server (NTRS)

    Bokerman, Gary (Inventor); Mohajeri, Nahid (Inventor); Muradov, Nazim (Inventor); Tabatabaie-Raissi, Ali (Inventor)

    2013-01-01

    A (H2) sensor composition includes a gas permeable matrix material intermixed and encapsulating at least one chemochromic pigment. The chemochromic pigment produces a detectable change in color of the overall sensor composition in the presence of H2 gas. The matrix material provides high H2 permeability, which permits fast permeation of H2 gas. In one embodiment, the chemochromic pigment comprises PdO/TiO2. The sensor can be embodied as a two layer structure with the gas permeable matrix material intermixed with the chemochromic pigment in one layer and a second layer which provides a support or overcoat layer.

  8. Measuring Permeability of Composite Cryotank Laminants

    NASA Technical Reports Server (NTRS)

    Oliver, Stanley T.; Selvidge, Shawn; Watwood, Michael C.

    2004-01-01

    This paper describes a test method developed to identify whether certain materials and material systems are suitable candidates for large pressurized reusable cryogenic tanks intended for use in current and future manned launch systems. It provides a quick way to screen numerous candidate materials for permeability under anticipated loading environments consistent with flight conditions, as well as addressing reusability issues. cryogenic tank, where the major design issue was hydrogen permeability. It was successfully used to evaluate samples subjected to biaxial loading while maintaining test temperatures near liquid hydrogen. After each sample was thermally preconditioned, a cyclic pressure load was applied to simulate the in-plane strain. First permeability was measured while a sample was under load. Then the sample was unloaded and allowed to return to ambient temperature. The test was repeated to simulate reusability, in order to evaluate its effects on material permeability.

  9. ULTRASTRUCTURE AND PERMEABILITY OF NUCLEAR MEMBRANES

    PubMed Central

    Wiener, Joseph; Spiro, David; Loewenstein, Werner R.

    1965-01-01

    The fine structures of nuclear envelopes known to have different permeability properties were compared. Membranes of salivary gland cell nuclei of Drosophila (third instar) and Chironomus (prepupae), which are strong barriers to ion diffusion, and membranes of oocyte nuclei (germinal vesicle) of Xenopus and Triturus, which are much more ion-permeable, show no essential difference in size, frequency, and distribution of their membrane gaps ("pores") which could account for the marked disparities in membrane permeability. The gaps are occupied by diffuse electron-opaque material with occasional central regions of strong opacity. This material may possibly account for the high diffusion resistance of Drosophila and Chironomus nuclear envelopes, where the resistance is far too great to allow free diffusion through the gaps. But material of this kind is also present in the more permeable nuclear envelopes of Xenopus and Triturus oocytes, and there are no convincing structural differences discernible with the techniques employed. PMID:5892850

  10. Variability of permeability with diameter of conduit

    NASA Astrophysics Data System (ADS)

    Adegoke, J. A.; Olowofela, J. A.

    2008-05-01

    An entry length is always observed before laminar flow is achieved in fluid flowing in a conduit. This depends on the Reynolds number of the flow and the degree of smoothness of the conduit. This work examined this region and the point where laminar flow commences in the context of flow through conduit packed with porous material like beads, of known porosity. Using some theoretical assumptions, it is demonstrated that permeability varies from zero at wall-fluid boundary to maximum at mid-stream, creating a permeability profile similar to the velocity profile. An equation was obtained to establish this. We also found that peak values of permeability increase with increasing porosity, and therefore entry length increases with increasing porosity with all other parameters kept constant. A plot of peak permeability versus porosity revealed that they are linearly related.

  11. Permeability After Impact Testing of Composite Laminates

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    2003-01-01

    Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

  12. Permeability After Impact Testing of Composite Laminates

    NASA Technical Reports Server (NTRS)

    Nettles, A.T.; Munafo, Paul (Technical Monitor)

    2002-01-01

    Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

  13. The Edison Environmental Center Permeable Pavement Site

    EPA Science Inventory

    This a presentation for a Community Outreach Event called "Chemistry Works and Celebration of International Year of Chemistry." It will review the permeable pavement research project at the Edison Environmental center.

  14. Flexible Sandwich Diaphragms Are Less Permeable

    NASA Technical Reports Server (NTRS)

    Michalovic, John G.; Vassallo, Franklin A.

    1993-01-01

    Diaphragms for use in refrigerator compressors made as laminates of commercially available elastomers and metals. Diaphragms flexible, but less permeable by chlorofluorocarbon refrigerant fluids than diaphragms made of homogeneous mixtures of materials.

  15. Regulation of endothelial permeability by second messengers.

    PubMed

    Siflinger-Birnboim, A; Malik, A B

    1996-02-01

    The mechanisms by which mediators such as oxidants released by neutrophil (PMN) activation increase endothelial permeability are poorly understood. The focus of this article is to identify some of these mechanisms. Studies using endothelial cell monolayers in culture have shown that PMN activation increases endothelial permeability both in the presence and absence of PMN-endothelial monolayer contact. Hydrogen peroxide (H2O2), an oxidant released by PMN activation, plays an important role in PMN-induced increases in endothelial permeability. The results of these studies suggest that, as with other mediators of inflammation (e.g., histamine, thrombin) the mechanism of H2O2-induced increase in endothelial permeability involves activation of endothelial protein kinase C (PKC) and increase in endothelial cytosolic Ca2+.

  16. NASA In-step: Permeable Membrane Experiment

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Viewgraphs on the Permeable Membrane Experiment are presented. An experiment overview is given. The Membrane Phase Separation Experiment, Membrane Diffusion Interference Experiment, and Membrane Wetting Experiment are described. Finally, summary and conclusions are discussed.

  17. Lunar electrical conductivity and magnetic permeability

    NASA Technical Reports Server (NTRS)

    Dyal, P.; Parkin, C. W.; Daily, W. D.

    1975-01-01

    Improved analytical techniques are applied to a large Apollo magnetometer data set to yield values of electroconductivity, temperature, magnetic permeability, and iron abundance. Average bulk electroconductivity of the moon is calculated to be .0007 mho/m; a rapid increase with depth to about .003 mho/m within 250 km is indicated. The temperature profile, obtained from the electroconductivity profile for olivine, indicates high lunar temperatures at relatively shallow depths. Magnetic permeability of the moon relative to its environment is calculated to be 1.008 plus or minus .005; a permeability relative to free space of 1.012 plus 0.011, minus 0.008 is obtained. Lunar iron abundances corresponding to this permeability value are 2.5 plus 2.3, minus 1.7 wt% free iron and 5.0-13.5 wt% total iron for a moon composed of a combination of free iron, olivine, and orthopyroxene.

  18. Permeability of rayon based polymer composites

    NASA Technical Reports Server (NTRS)

    Stokes, E. H.

    1992-01-01

    Several types of anomalous rayon based phenolic behavior have been observed in post-fired nozzles and exit cones. Many of these events have been shown to be related to the development of internal gas pressure within the material. The development of internal gas pressure is a function of the amount of gas produced within the material and the rate at which that gas is allowed to escape. The latter property of the material is referred to as the material's permeability. The permeability of two dimensional carbonized rayon based phenolic composites is a function of material direction, temperature, and stress/strain state. Recently significant differences in the permeability of these materials has been uncovered which may explain their inconsistent performance. This paper summarizes what is known about the permeability of these materials to date and gives possible implications of these finding to the performance of these materials in an ablative environment.

  19. Pneumatic fracturing of low permeability media

    SciTech Connect

    Schuring, J.R.

    1996-08-01

    Pneumatic fracturing of soils to enhance the removal and treatment of dense nonaqueous phase liquids is described. The process involves gas injection at a pressure exceeding the natural stresses and at a flow rate exceeding the permeability of the formation. The paper outlines geologic considerations, advantages and disadvantages, general technology considerations, low permeability media considerations, commercial availability, efficiency, and costs. Five case histories of remediation using pneumatic fracturing are briefly summarized. 11 refs., 2 figs., 1 tab.

  20. Silicic Magma Degassing: A High Temperature Experimental Insight into Permeability Evolution

    NASA Astrophysics Data System (ADS)

    Chadderton, A. L.; Sammonds, P. R.; Meredith, P. G.; Smith, R.; Tuffen, H.; Gaunt, H. E.

    2015-12-01

    Experimentally determined permeability results have provided the basis for numerous theories of magmatic degassing. Two recent eruptions in Chile, at Chaitén Volcano in 2008-10 and Cordón Caulle in 2011-12, allowed the first detailed observations of rhyolitic activity and provided insights into the evolution of highly silicic eruptions. Both events exhibited simultaneous explosive and effusive activity, with both lava and ash plumes emitted from the same vent [1]. The permeability of fracture networks that act as fluid flow pathways is key to understanding such eruptive behaviour. Here, we report results from a systematic experimental investigation of permeability in volcanic rocks, at magmatic temperatures and pressures, in the presence of pore fluids using our newly-developed high-temperature permeability facility. Enhancements to the High Temperature Triaxial Deformation Cell at UCL [2] have enabled us to make permeability measurements on 25mm x 50mm cores at both elevated temperature and elevated hydrostatic pressure [3]. We present results from several suites of permeability measurements on samples of dome dacite from the 2004-08 eruption of Mount St Helens, and rhyolite collected from the lava dome formed during the 2008-10 eruption of Chaitén, Chile. Tests were conducted at temperatures up to 900oC and under an effective pressure of 5 MPa, using the steady-state flow technique. Samples were cooled to room temperature between each high temperature test, and the permeability of each sample was re-measured before heating to the next temperature increment in the series. The results show a complex permeability evolution that includes a reduction in permeability by approximately 4 orders of magnitude up to 600oC. Together with TGA, FTIR and hot-stage data, these new experimental permeability results are applied to enhance our understanding of the complex issue of silicic magma degassing. [1] Castro JM et al, 2014 EPSL 405, 52-61 [2] Rocchi V et al, 2004 JVGR

  1. Fracture-permeability behavior of shale

    SciTech Connect

    Carey, J. William; Lei, Zhou; Rougier, Esteban; Mori, Hiroko; Viswanathan, Hari

    2015-05-08

    The fracture-permeability behavior of Utica shale, an important play for shale gas and oil, was investigated using a triaxial coreflood device and X-ray tomography in combination with finite-discrete element modeling (FDEM). Fractures generated in both compression and in a direct-shear configuration allowed permeability to be measured across the faces of cylindrical core. Shale with bedding planes perpendicular to direct-shear loading developed complex fracture networks and peak permeability of 30 mD that fell to 5 mD under hydrostatic conditions. Shale with bedding planes parallel to shear loading developed simple fractures with peak permeability as high as 900 mD. In addition to the large anisotropy in fracture permeability, the amount of deformation required to initiate fractures was greater for perpendicular layering (about 1% versus 0.4%), and in both cases activation of existing fractures are more likely sources of permeability in shale gas plays or damaged caprock in CO₂ sequestration because of the significant deformation required to form new fracture networks. FDEM numerical simulations were able to replicate the main features of the fracturing processes while showing the importance of fluid penetration into fractures as well as layering in determining fracture patterns.

  2. Fracture-permeability behavior of shale

    DOE PAGES

    Carey, J. William; Lei, Zhou; Rougier, Esteban; Mori, Hiroko; Viswanathan, Hari

    2015-05-08

    The fracture-permeability behavior of Utica shale, an important play for shale gas and oil, was investigated using a triaxial coreflood device and X-ray tomography in combination with finite-discrete element modeling (FDEM). Fractures generated in both compression and in a direct-shear configuration allowed permeability to be measured across the faces of cylindrical core. Shale with bedding planes perpendicular to direct-shear loading developed complex fracture networks and peak permeability of 30 mD that fell to 5 mD under hydrostatic conditions. Shale with bedding planes parallel to shear loading developed simple fractures with peak permeability as high as 900 mD. In addition tomore » the large anisotropy in fracture permeability, the amount of deformation required to initiate fractures was greater for perpendicular layering (about 1% versus 0.4%), and in both cases activation of existing fractures are more likely sources of permeability in shale gas plays or damaged caprock in CO₂ sequestration because of the significant deformation required to form new fracture networks. FDEM numerical simulations were able to replicate the main features of the fracturing processes while showing the importance of fluid penetration into fractures as well as layering in determining fracture patterns.« less

  3. Modulation of ConA-induced inflammatory ascites by histamine - short communication.

    PubMed

    Baintner, Károly

    2015-03-01

    The early phase of the ConA-induced inflammatory ascites was studied, with special reference to histamine. Concanavalin A (ConA), a cell-surface binding lectin was injected i.p. (25 mg/kg bw) to mice. After 1 h the animals were killed, the ascitic fluid collected and measured. Other agents were injected s.c., 10 min before the ConA-challenge. Exogenous histamine markedly inhibited the ConA-induced ascites. Release of endogenous vasoactive agents from the mast cells by Compound 48/80 had a similar, but slight effect. Cromolyn, a mast cell stabilizing agent, and chloropyramine, a histamine H1 receptor antagonist was ineffective. Although histamine increases endothelial permeability, it did not enhance the formation of ascitic fluid, on the contrary, it inhibited the ConA-induced ascites, presumably due to its known hypotonic effect. It is concluded that ConA-induced ascites is not mediated by mast cell histamine.

  4. Comparative field permeability measurement of permeable pavements using ASTM C1701 and NCAT permeameter methods.

    PubMed

    Li, Hui; Kayhanian, Masoud; Harvey, John T

    2013-03-30

    Fully permeable pavement is gradually gaining support as an alternative best management practice (BMP) for stormwater runoff management. As the use of these pavements increases, a definitive test method is needed to measure hydraulic performance and to evaluate clogging, both for performance studies and for assessment of permeability for construction quality assurance and maintenance needs assessment. Two of the most commonly used permeability measurement tests for porous asphalt and pervious concrete are the National Center for Asphalt Technology (NCAT) permeameter and ASTM C1701, respectively. This study was undertaken to compare measured values for both methods in the field on a variety of permeable pavements used in current practice. The field measurements were performed using six experimental section designs with different permeable pavement surface types including pervious concrete, porous asphalt and permeable interlocking concrete pavers. Multiple measurements were performed at five locations on each pavement test section. The results showed that: (i) silicone gel is a superior sealing material to prevent water leakage compared with conventional plumbing putty; (ii) both methods (NCAT and ASTM) can effectively be used to measure the permeability of all pavement types and the surface material type will not impact the measurement precision; (iii) the permeability values measured with the ASTM method were 50-90% (75% on average) lower than those measured with the NCAT method; (iv) the larger permeameter cylinder diameter used in the ASTM method improved the reliability and reduced the variability of the measured permeability.

  5. Maturation of rat proximal tubule chloride permeability.

    PubMed

    Baum, Michel; Quigley, Raymond

    2005-12-01

    We have previously shown that neonate rabbit tubules have a lower chloride permeability but comparable mannitol permeability compared with adult proximal tubules. The surprising finding of lower chloride permeability in neonate proximals compared with adults impacts net chloride transport in this segment, which reabsorbs 60% of the filtered chloride in adults. However, this maturational difference in chloride permeability may not be applicable to other species. The present in vitro microperfusion study directly examined the chloride and mannitol permeability using in vitro perfused rat proximal tubules during postnatal maturation. Whereas there was no maturational change in mannitol permeability, chloride permeability was 6.3 +/- 1.3 x 10(-5) cm/s in neonate rat proximal convoluted tubule and 16.1 +/- 2.3 x 10(-5) cm/s in adult rat proximal convoluted tubule (P < 0.01). There was also a maturational increase in chloride permeability in the rat proximal straight tubule (5.1 +/- 0.6 x 10(-5) cm/s vs. 9.3 +/- 0.6 x 10(-5) cm/s, P < 0.01). There was no maturational change in bicarbonate-to-chloride permeabilities (P(HCO3)/P(Cl)) in the rat proximal straight tubules (PST) and proximal convoluted tubules (PCT) or in the sodium-to-chloride permeability (P(Na)/P(Cl)) in the proximal straight tubule; however, there was a significant maturational decrease in proximal convoluted tubule P(Na)/P(Cl) with postnatal development (1.31 +/- 0.12 in neonates vs. 0.75 +/- 0.06 in adults, P < 0.001). There was no difference in the transepithelial resistance measured by current injection and cable analysis in the PCT, but there was a maturational decrease in the PST (7.2 +/- 0.8 vs. 4.6 +/- 0.1 ohms x cm2, P < 0.05). These studies demonstrate there are maturational changes in the rat paracellular pathway that impact net NaCl transport during development. PMID:16051720

  6. Permeability reduction in granite under hydrothermal conditions

    USGS Publications Warehouse

    Morrow, C.A.; Moore, Diane E.; Lockner, D.A.

    2001-01-01

    The formation of impermeable fault seals between earthquake events is a feature of many models of earthquake generation, suggesting that earthquake recurrence may depend in part on the rate of permeability reduction of fault zone materials under hydrothermal conditions. In this study, permeability measurements were conducted on intact, fractured, and gouge-bearing Westerly granite at an effective pressure of 50 MPa and at temperatures from 150?? to 500??C, simulating conditions in the earthquake-generating portions of fault zones. Pore fluids were cycled back and forth under a 2 MPa pressure differential for periods of up to 40 days. Permeability of the granite decreased with time t, following the exponential relation k = c(10-rt). For intact samples run between 250?? and 500??C the time constant for permeability decrease r was proportional to temperature and ranged between 0.001 and 0.1 days-1 (i.e., between 0.4 and 40 decades year-1 loss of permeability). Values of r for the lower-temperature experiments differed little from the 250??C runs. In contrast, prefractured samples showed higher rates of permeability decrease at a given temperature. The surfaces of the fractured samples showed evidence of dissolution and mineral growth that increased in abundance with both temperature and time. The experimentally grown mineral assemblages varied with temperature and were consistent with a rock-dominated hydrothermal system. As such mineral deposits progressively seal the fractured samples, their rates of permeability decrease approach the rates for intact rocks at the same temperature. These results place constraints on models of precipitation sealing and suggest that fault rocks may seal at a rate consistent with earthquake recurrence intervals of typical fault zones.

  7. Strain-dependent permeability of volcanic rocks.

    NASA Astrophysics Data System (ADS)

    Farquharson, Jamie; Heap, Michael; Baud, Patrick

    2016-04-01

    We explore permeability evolution during deformation of volcanic materials using a suite of rocks with varying compositions and physical properties (such as porosity ϕ). 40 mm × 20 mm cylindrical samples were made from a range of extrusive rocks, including andesites from Colima, Mexico (ϕ˜0.08; 0.18; 0.21), Kumamoto, Japan (ϕ˜0.13), and Ruapehu, New Zealand (ϕ˜0.15), and basalt from Mt Etna, Italy (ϕ˜0.04). Gas permeability of each sample was measured before and after triaxial deformation using a steady-state benchtop permeameter. To study the strain-dependence of permeability in volcanic rocks, we deformed samples to 2, 3, 4, 6, and 12 % axial strain at a constant strain rate of 10‑5 s‑1. Further, the influence of failure mode - dilatant or compactant - on permeability was assessed by repeating experiments at different confining pressures. During triaxial deformation, porosity change of the samples was monitored by a servo-controlled pore fluid pump. Below an initial porosity of ˜0.18, and at low confining pressures (≤ 20 MPa), we observe a dilatant failure mode (shear fracture formation). With increasing axial strain, stress is accommodated by fault sliding and the generation of ash-sized gouge between the fracture planes. In higher-porosity samples, or at relatively higher confining pressures (≥ 60 MPa), we observe compactant deformation characterised by a monotonous decrease in porosity with increasing axial strain. The relative permeability k' is given by the change in permeability divided by the initial reference state. When behaviour is dilatant, k' tends to be positive: permeability increases with progressive deformation. However, results suggest that after a threshold amount of strain, k' can decrease. k' always is negative (permeability decreases during deformation) when compaction is the dominant behaviour. Our results show that - in the absence of a sealing or healing process - the efficiency of a fault to transmit fluids is

  8. Gastrointestinal permeability in patients with irritable bowel syndrome assessed using a four probe permeability solution

    PubMed Central

    Del Valle-Pinero, Arseima Y.; Van Deventer, Hendrick E.; Fourie, Nicolaas H.; Martino, Angela C.; Patel, Nayan S.; Remaley, Alan T.; Henderson, Wendy A.

    2013-01-01

    Background Abnormal gastrointestinal permeability has been linked to irritable bowel syndrome (IBS). The lactulose-to-mannitol ratio is traditionally used to assess small intestine permeability while sucralose and sucrose are used to assess colonic and gastric permeability respectively. We used a single 4-probe test solution to assess permeability throughout the gastrointestinal tract in IBS patients and healthy controls by measuring the recovery of the probes in urine after ingestion using a modified liquid chromatography mass spectrometry protocol. Methods Fasting participants (N = 59) drank a permeability test solution (100 ml: sucralose, sucrose, mannitol, and lactulose). Urine was collected over a 5-h period and kept frozen until analysis. Urinary sugar concentrations were measured using an liquid chromatography/triple quadruple mass spectrometer. Results Colonic permeability was significantly lower in IBS patients when compared to healthy controls (p = 0.011). Gastric and small intestinal permeability did not significantly differ between the groups. Conclusions The study demonstrates the clinical potential of this non-invasive method for assessing alterations in gastrointestinal permeability in patients with IBS. PMID:23328210

  9. Changes in permeability caused by earthquakes

    NASA Astrophysics Data System (ADS)

    Manga, Michael; Wang, Chi-Yuen; Shi, Zheming

    2016-04-01

    Earthquakes induce a range of hydrological responses, including changes in streamflow and changes in the water level in wells. Here we show that many of these responses are caused the changes in permeability produced by the passage of seismic waves. First we analyze streams that were dry or nearly dry before the 2014 M6 Napa, California, earthquake butstarted to flow after the earthquake. We show that the new flows were meteoric in origin and originate in the nearby mountains. Responses are not correlated with the sign of static strains implying seismic waves liberated this water, presumably by changing permeability. We also analyze a large network of wells in China that responded to 4 large earthquakes. We monitor permeability changes through their effect on the water level response to solid Earth tides. We find that when earthquakes produce sustained changes in water level, permeability also changes. Wells with water level changes that last for only days show no evidence for changes in aquifer permeability.

  10. Honeycomb Core Permeability Under Mechanical Loads

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Raman, V. V.; Venkat, Venki S.; Sankaran, Sankara N.

    1997-01-01

    A method for characterizing the air permeability of sandwich core materials as a function of applied shear stress was developed. The core material for the test specimens was either Hexcel HRP-3/16-8.0 and or DuPont Korex-1/8-4.5 and was nominally one-half inch thick and six inches square. The facesheets where made of Hercules' AS4/8552 graphite/epoxy (Gr/Ep) composites and were nominally 0.059-in. thick. Cytec's Metalbond 1515-3M epoxy film adhesive was used for co-curing the facesheets to the core. The permeability of the specimens during both static (tension) and dynamic (reversed and non-reversed) shear loads were measured. The permeability was measured as the rate of air flow through the core from a circular 1-in2 area of the core exposed to an air pressure of 10.0 psig. In both the static and dynamic testing, the Korex core experienced sudden increases in core permeability corresponding to a core catastrophic failure, while the URP core experienced a gradual increase in the permeability prior to core failure. The Korex core failed at lower loads than the HRP core both in the transverse and ribbon directions.

  11. Permeability of Rigid Fibrous Refractory Insulations

    NASA Technical Reports Server (NTRS)

    Marschall, J.; Milos, F. S.; Rasky, Daniel J. (Technical Monitor)

    1996-01-01

    Rigid fibrous refractory insulations (TPS tiles) are integral components of many spacecraft thermal protection systems. These materials are composed of refractory fibers With diameters on the order of 1 to 15 micrometers. They are lightweight and have an open, highly porous microstructure. Typical densities are less than 500 kilograms per cubic meters, and porosities generally exceed 0.8. Because of their open porosity, these materials are permeable to gas glow. There are numerous instances in which internal gas transport in a thermal protection system could be important; examples include the penetration of hot boundary-layer gases into the insulation, the flow of decomposition (pyrolysis) products from the interior, the use of convective flows to mitigate ice formation caused by cryopumping, and the design of refractory vents for pressure equilibration during atmospheric entry. Computational analysis of gas flow through porous media requires values of permeability which have not previously been available for the rigid fibrous insulations used in thermal protection systems. This paper will document measurements of permeability for a variety of insulations from NASA's LI, FRCI, and AETB families of lightweight ceramic ablators. The directional anisotropy of permeability and its dependence on gas pressure and material density will be presented. It will be shown that rarified-flow effects are significant in the flow through such materials. Connections will be drawn between the insulation microstructure and permeability. The paper will also include representative computations of flow through rigid fibrous insulations.

  12. Permeability evolution in sandstone: Digital rock approach

    NASA Astrophysics Data System (ADS)

    Kameda, Ayako

    Permeability is perhaps one of the most important yet elusive reservoir properties, since it poorly correlates with elastic properties, and as a result, cannot be mapped remotely. Physical permeability measurements may be augmented or even partially replaced by numerical experiments, provided that a numerical simulation accurately mimics the physical process. Numerical simulation of laboratory experiments on rocks, or digital rock physics, is an emerging field that may benefit the petroleum industry. For numerical experimentation to find its way into the mainstream, it has to be practical and easily repeatable, i.e., implemented on standard hardware and in real time. This condition reduces the feasible size of a digital sample to just a few grains across. Will the results be meaningful for a larger rock volume? The answer is that small fragments of medium- to high-porosity sandstone, such as cuttings, which are not statistically representative of a larger sample, cannot be used to numerically calculate the exact porosity and permeability of the sample. However, by using a significant number of such small fragments, it may be possible to establish a site-specific permeability-porosity trend, which can be used to estimate the absolute permeability from independent porosity data, obtained in the well or inferred from seismic measurements.

  13. Gas Permeability in Rubbery Polyphosphazene Membranes

    SciTech Connect

    Frederick F. Stewart; Christopher J. Orme; John R. Klaehn; Mason K. Harrup; Thomas A. Luther; Eric S. Peterson

    2006-09-01

    The synthesis, characterization, and gas permeability of ten new polyphosphazenes has been studied. Additionally, the first gas permeation data has been collected on hydrolytically unstable poly[bis-(chloro)phosphazene]. Gases used in this study include CO2, CH4, O2, N2, H2, and Ar. CO2 was the most permeable gas through any of the phosphazenes and a direct correlation between the Tg of the polymer and CO2 transport was noted with permeability increasing with decreasing polymer Tg. To a lesser degree, permeability of all the other gases studied also yielded increases with decreasing polymer Tg. The trend observed for these new polymers was further supported by published data for other phosphazenes. Furthermore, permeability data for all gases were found to correlate to the gas condensability and the gas critical pressures, except for hydrogen, suggesting that the nature of the gas is also a significant factor for permeation through rubbery phosphazene membranes. Ideal separation factors (á) for the CO2/H2 and CO2/CH4 gas pairs were calculated. For CO2/CH4, no increase in á was observed with decreasing Tg, however increases in á were noted for the CO2/H2 pair.

  14. GROUNDWATER FLOW IN LOW-PERMEABILITY ENVIRONMENTS.

    USGS Publications Warehouse

    Neuzil, C.E.

    1986-01-01

    Certain geologic media are known to have small permeability; subsurface environments composed of these media and lacking well developed secondary permeability have groundwater flow systems with many distinctive characteristics. Moreover, groundwater flow in these environments appears to influence the evolution of certain hydrologic, geologic, and geochemical systems, may affect the accumulation of petroleum and ores, and probably has a role in the structural evolution of parts of the crust. Such environments are also important in the context of waste disposal. This review attempts to synthesize the diverse contributions of various disciplines to the problem of flow in low-permeability environments. Problems hindering analysis are enumerated together with suggested approaches to overcoming them. A common thread running through the discussion is the significance of size- and time-scale limitations of the ability to directly observe flow behavior and make significance of size- and time-scale limitations of the ability to directly observe flow behavior and make measurements of parameters.

  15. Blood flow and permeability in microvessels

    NASA Astrophysics Data System (ADS)

    Sugihara-Seki, Masako; Fu, Bingmei M.

    2005-07-01

    The mechanics of blood flow in microvessels and microvessel permeability are reviewed. In the first part, characteristics of blood flow in vivo and in vitro are described from a fluid-mechanical point of view, and mathematical models for blood flow in microvessels are presented. Possible causes of the increased flow resistance obtained in vivo compared to in vitro are examined, including the effects of irregularities of vessel lumen, the presence of endothelial surface glycocalyx and white blood cells. In the second part, the ultrastructural pathways and mechanisms whereby endothelial cells and the clefts between the cells modulate microvessel permeability to water and solutes are introduced. Previous and current models for microvessel permeability to water and solutes are reviewed. These models examine the role of structural components of interendothelial cleft, such as junction strands and surface glycocalyx, in the determination of water and solute transport across the microvessel walls. Transport models in the tissue space surrounding the microvessel are also described.

  16. Virtual screening of intestinal drug permeability.

    PubMed

    Stenberg, P; Luthman, K; Artursson, P

    2000-03-01

    Lead compounds generated in high throughput drug discovery programmes often have unfavorable biopharmaceutical properties, resulting in a low success rate of such drug candidates in clinical development. Drug companies and researchers would thus like to have methods of predicting biopharmaceutical properties accurately. The intestinal permeability to a lead compound is one such property which is particularly important. Therefore, access to methods to accurately predict biopharmaceutical properties, such as the intestinal permeability of a large series of compounds, is of particular importance. This review deals with new theoretical methods used to predict intestinal drug permeability. There are several possible transport routes across the intestine, but theoretical methods generally deal with only one of them, the passive transcellular route. Therefore, this review will also discuss the relative importance of passive and active drug transport and efflux routes using recent data generated in cell cultures, animal models and human subjects.

  17. In situ permeability testing of rock salt

    SciTech Connect

    Peterson, E.W.; Lagus, P.L.; Broce, R.D.; Lie, K.

    1981-04-01

    Storage of transuranic (TRU) wastes in bedded salt formations requires a knowledge of the in situ permeability of SENM rock salt. Since assumptions for safety assessments have been made in which these wastes could generate gas pressures on the order of the lithostatic pressure over geologic time scales, the permeability of the surrounding formation becomes an important parameter for determining the manner in which the gases will be contained or dispersed. This report describes the series of tests conducted in the AEC-7 borehole, located near the WIPP site, to determine the in situ gas flow characteristics of the bedded salt. In these tests, compressed air was injected into the borehole and flow into the surrounding formation measured. These measured flow rates were interpreted in terms of formation permeabilities and porosities which were, in turn, used as modeling parameters for the repository response analysis. Two series of field tests were performed. The first series consisted of a number of whole-hole flow tests conducted to provide preliminary design information required for future operation of a guarded straddle packer system capable of measuring permeabilities > or = 0.1 ..mu..darcy. The second series of tests were conducted using the Systems, Science and Software (S-Cubed) designed guarded straddle packer system. In these interval permeability tests, 100-foot lengths of borehole were isolated and the flow characteristics of the surrounding formation examined. In this report, a complete description of the test procedures, instrumentation, and measurement techniques is first given. The analytical/numerical methods used for data interpretation are then presented, followed by results of the interval and permeability tests. (The whole-hole tests are summarized in Appendix A.) Conclusions are presented in the final section.

  18. Lunar magnetic permeability studies and magnetometer sensitivity

    NASA Technical Reports Server (NTRS)

    King, J. H.; Ness, N. F.

    1977-01-01

    A regression of quiet magnetic field components simultaneously measured by the two Explorer 35 magnetometers reveals uncertainties in effective sensitivity factors of up to a few percent in one or both of these instruments. Given this, the validity of previous lunar permeability studies based on Explorer 35/ALSEP regressions, wherein inferences are drawn from regression line slopes differing from unity by the order of one percent, is called into question. We emphasize the need to critically address the question of small deviations in magnetometer sensitivity factors from nominal values as a part of any two-magnetometer lunar permeability study.

  19. Magnetic permeability measurements and a lunar core

    NASA Technical Reports Server (NTRS)

    Goldstein, B. E.; Phillips, R. J.; Russell, C. T.

    1976-01-01

    Measurements of the magnetic field induced in the moon while it is in the geomagnetic tail lobes have been interpreted in terms of lunar magnetic permeability due to free iron content; such studies ignored the possibility that a highly conducting lunar core (Fe or FeS) would exclude magnetic fields with an apparent diamagnetic effect. Using lunar chemical and thermal models to determine plausible limits of magnetic permeability, we interpret measurements of the induced moment. The maximum likely radius of a lunar core is 580 km. Subsatellite and ALSEP measurements of the induced field are in disagreement. Resolving the differences is critical to determining whether a core could or does exist.

  20. Development of an Improved Permeability Modification Simulator

    SciTech Connect

    Gao, H.W.; Elphnick, J.

    1999-03-09

    This report describes the development of an improved permeability modification simulator performed jointly by BDM Petroleum Technologies and Schlumberger Dowell under a cooperative research and development agreement (CRADA) with the US Department of Energy. The improved simulator was developed by modifying NIPER's PC-GEL permeability modification simulator to include a radial model, a thermal energy equation, a wellbore simulator, and a fully implicit time-stepping option. The temperature-dependent gelation kinetics of a delayed gel system (DGS) is also included in the simulator.

  1. Predicting the permeability of sediments entering subduction zones

    NASA Astrophysics Data System (ADS)

    Daigle, Hugh; Screaton, Elizabeth J.

    2015-07-01

    Using end-member permeabilities defined by a worldwide compilation of sediment permeabilities at convergent margins, we compare permeability predictions using a geometric mean and a two-component effective medium theory (EMT). Our implementation of EMT includes a threshold fraction of the high-permeability component that determines whether flow occurs dominantly in the high- or low-permeability component. We find that this threshold fraction in most cases is equal to the silt + sand-sized fraction of the sediment. This suggests that sediments undergoing primary consolidation tend to exhibit flow equally distributed between the high- and low-permeability components. We show that the EMT method predicts permeability better than the weighted geometric mean of the end-member values for clay fractions <0.6. This work provides insight into the microstructural controls on permeability in subducting sediments and valuable guidance for locations which lack site-specific permeability results but have available grain-size information.

  2. Nam Con Son Basin

    SciTech Connect

    Tin, N.T.; Ty, N.D.; Hung, L.T.

    1994-07-01

    The Nam Con Son basin is the largest oil and gas bearing basin in Vietnam, and has a number of producing fields. The history of studies in the basin can be divided into four periods: Pre-1975, 1976-1980, 1981-1989, and 1990-present. A number of oil companies have carried out geological and geophysical studies and conducted drilling activities in the basin. These include ONGC, Enterprise Oil, BP, Shell, Petro-Canada, IPL, Lasmo, etc. Pre-Tertiary formations comprise quartz diorites, granodiorites, and metamorphic rocks of Mesozoic age. Cenozoic rocks include those of the Cau Formation (Oligocene and older), Dua Formation (lower Miocene), Thong-Mang Cau Formation (middle Miocene), Nam Con Son Formation (upper Miocene) and Bien Dong Formation (Pliocene-Quaternary). The basement is composed of pre-Cenozoic formations. Three fault systems are evident in the basin: north-south fault system, northeast-southwest fault system, and east-west fault system. Four tectonic zones can also be distinguished: western differentiated zone, northern differentiated zone, Dua-Natuna high zone, and eastern trough zone.

  3. Vascular Permeability and Drug Delivery in Cancers

    PubMed Central

    Azzi, Sandy; Hebda, Jagoda K.; Gavard, Julie

    2013-01-01

    The endothelial barrier strictly maintains vascular and tissue homeostasis, and therefore modulates many physiological processes such as angiogenesis, immune responses, and dynamic exchanges throughout organs. Consequently, alteration of this finely tuned function may have devastating consequences for the organism. This is particularly obvious in cancers, where a disorganized and leaky blood vessel network irrigates solid tumors. In this context, vascular permeability drives tumor-induced angiogenesis, blood flow disturbances, inflammatory cell infiltration, and tumor cell extravasation. This can directly restrain the efficacy of conventional therapies by limiting intravenous drug delivery. Indeed, for more effective anti-angiogenic therapies, it is now accepted that not only should excessive angiogenesis be alleviated, but also that the tumor vasculature needs to be normalized. Recovery of normal state vasculature requires diminishing hyperpermeability, increasing pericyte coverage, and restoring the basement membrane, to subsequently reduce hypoxia, and interstitial fluid pressure. In this review, we will introduce how vascular permeability accompanies tumor progression and, as a collateral damage, impacts on efficient drug delivery. The molecular mechanisms involved in tumor-driven vascular permeability will next be detailed, with a particular focus on the main factors produced by tumor cells, especially the emblematic vascular endothelial growth factor. Finally, new perspectives in cancer therapy will be presented, centered on the use of anti-permeability factors and normalization agents. PMID:23967403

  4. Tailoring wall permeabilities for enhanced filtration

    NASA Astrophysics Data System (ADS)

    Herterich, J. G.; Vella, D.; Field, R. W.; Hankins, N. P.; Griffiths, I. M.

    2015-05-01

    The build-up of contaminants at the wall of cross-flow membrane filtration systems can be detrimental to the operation of such systems because of, amongst other things, the osmotic backflow it may induce. In this paper, we propose a strategy to avoid the negative effects of backflow due to osmosis by using 2D channels bounded by walls with a combination of permeable and impermeable segments. We show that preventing flow through the final portion of the channel can increase the efficiency of filtration and we determine the optimal fraction occupied by the permeable wall that maximizes efficiency. Our analysis uses a combination of numerical techniques and asymptotic analysis in the limit of low wall permeabilities. Finally, we consider how the energy cost of filtration depends on the Péclet number and show that the energy cost per unit of filtered water may be minimized by appropriately choosing both the Péclet number and the permeable-region fraction.

  5. [Graphic recording of the maxillary ostium permeability].

    PubMed

    Rosique, M; Pastor, A; Hellín, D; García-Ortega, F P

    1993-01-01

    Currently we practise salpingography for evaluating Eustachian tube permeability. In a similar mode, we describe a technique of graphic search, with impedianciometry, of patency in the osteomeatal complex, after puncture and placing Foley's catheter in the maxillary sinus. In several cases without opening, we make topical treatment though catheter. For this technique, we propose the term of infundibulography.

  6. Pump and treat in low permeability media

    SciTech Connect

    Mackay, D.M.

    1996-08-01

    Pump and Treat (P&T) is a commonly applied technology whose primary promise for the low permeability environments of interest to these technology reviews is almost certainly containment of the problem. Conventional P&T would be expected to offer little promise of complete restoration in such environments, unless very long time frames (decades or centuries) are considered. A variety of approaches have been proposed to enhance the efficiency of P&T; some appear to offer little promise in low or mixed permeability environments, while others may offer more promise (e.g. hydro- or pneumatic-fracturing, which are described elsewhere in this document, and application of vacuum to the extraction well(s), which is a proprietary technology whose promise is currently difficult to assess objectively). Understanding the potential advantages and means of optimizing these enhancement approaches requires more understanding of the basic processes limiting P&T performance in low or mixed permeability media. These efforts are probably also necessary to understand the advantages and means of optimizing many of the very different remedial technologies that may be applicable to low or mixed permeability environments. Finally, since a reasonably certain capability of P&T is containment (i.e. prevention of further migration of contaminants), P&T may generally be required as a sort of safety net around sites at which the alternative technologies are being tested or applied. 23 refs.

  7. Reduced hydrogen permeability at high temperatures

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Klopp, W. D.; Misencik, J. A.

    1981-01-01

    CO and CO2 reduce hydrogen loss through iron, nickel, and cobalt based alloy tubes. Method is based on concept that oxide film on metal surface reduces hydrogen permeability through metal; adding CO or CO2 forms oxide films continuously during operation, and hydrogen containment is improved. Innovation enhances prospects for Stirling engine system utilization.

  8. Permeability Measurements in Carbon-Epoxy Composites

    NASA Technical Reports Server (NTRS)

    Zdenek, Michael J.

    1999-01-01

    To determine the permeability of the composite feedline, that is proposed to be used in the X-33 Reusable Launch Vehicle (RLV), three 8 x 8-in. coupons were constructed. Two of the coupons were layed-up with 4 plies of plain weave prepreg [0/90, plus or minus 45, plus or minus 45, 0/90] and the other one layed-up with 4 plies of unidirectional prepreg [0, 90, 90, 0]. The coupons were vacuumed bagged and cured to manufactures specifications. The coupons were then placed in an apparatus to test for permeability. Nitrogen gas was used to permeate through the coupons at a pressure of 5 psig. A manometer was placed on the opposite side of the coupons and was used to measure the height of the fluid with respect to time. From this data the mass flow rate of the gas could be calculated since the area of the manometer and the density of the gas is known. The results of the test are given. The permeability constant was calculated using Darcy's law, which related the pressure drop, flow rate of the permeating gas and resistance to flow through the coupon created. To put the results into prospective the permeability of sand stone and granite is 1E-15 and 1E-20 respectively.

  9. Permeable pavement research – Edison, New Jersey

    EPA Science Inventory

    These are the slides for the New York City Concrete Promotional Council Pervious Concrete Seminar presentation. The basis for the project, the monitoring design and some preliminary monitoring data from the permeable pavement parking lot at the Edison Environmental Center are pre...

  10. EVALUATION OF PERMEABLE REACTIVE BARRIER PERFORMANCE

    EPA Science Inventory

    The permeable reactive barrier (PRB) technology represents a passive option for long-term treatment of ground-water contamination. PRBs are a potentially more cost-effective treatment option for a variety of dissolved contaminants, such as certain types of chlorinated solvents, ...

  11. SINGLE-INTERVAL GAS PERMEABILITY ESTIMATION

    EPA Science Inventory

    Single-interval, steady-steady-state gas permeability testing requires estimation of pressure at a screened interval which in turn requires measurement of friction factors as a function of mass flow rate. Friction factors can be obtained by injecting air through a length of pipe...

  12. A microdevice for parallelized pulmonary permeability studies.

    PubMed

    Bol, Ludivine; Galas, Jean-Christophe; Hillaireau, Hervé; Le Potier, Isabelle; Nicolas, Valérie; Haghiri-Gosnet, Anne-Marie; Fattal, Elias; Taverna, Myriam

    2014-04-01

    We describe a compartmentalized microdevice specifically designed to perform permeability studies across a model of lung barrier. Epithelial cell barriers were reproduced by culturing Calu-3 cells at the air-liquid interface (AIC) in 1 mm² microwells made from a perforated glass slide with an embedded porous membrane. We created a single basolateral reservoir for all microwells which eliminated the need to renew the growth medium during the culture growth phase. To perform drug permeability studies on confluent cell layers, the cell culture slide was aligned and joined to a collection platform consisting in 35 μL collection reservoirs connected at the top and bottom with microchannels. The integrity and functionality of the cell barriers were demonstrated by measurement of trans-epithelial electrical resistance (TEER), confocal imaging and permeability assays of ¹⁴C-sucrose. Micro-cell barriers were able to form confluent layers in 1 week, demonstrating a similar bioelectrical evolution as the Transwell systems used as controls. Tight junctions were observed throughout the cell-cell interfaces, and the low permeability coefficients of ¹⁴C-sucrose confirmed their functional presence, creating a primary barrier to the diffusion of solutes. This microdevice could facilitate the monitoring of biomolecule transport and the screening of formulations promoting their passage across the pulmonary barrier, in order to select candidates for pulmonary administration to patients. PMID:24337430

  13. Permeability during densification of viscous droplets

    NASA Astrophysics Data System (ADS)

    Wadsworth, Fabian; Vasseur, Jérémie; Llewellin, Ed; Dobson, Katherine; Schauroth, Jenny; Heap, Michael; Farquharson, Jamie; Scheu, Bettina; Kendrick, Jackie; Lavallée, Yan; von Aulock, Felix; Dingwell, Donald B.

    2016-04-01

    Fragmentation of magma can yield a transiently granular material, which can subsequently weld back to a fluid-continuum. This process results in dramatic changes in the porosity of the material, which impacts its fluid permeability. We collate published data for the porosity and permeability of volcanic and synthetic materials which have undergone this process to different amounts. By discriminating data for which good microstructural information are provided, we use simple scaling arguments to collapse the data in both the still-granular, high porosity region, and the fluid-continuum low porosity region, such that a universal description can be provided. This allows us to describe the microstructural meaning of permeability scaling, and to infer the controls on the position of this transition between dominantly granular (dispersion) and dominantly fluid-continuum materials. Fractures in coherent magmas are thought to be a primary degassing pathway in high viscosity systems. As a specific application, we consider transiently granular magma being transported through and deposited in these fractures. We finally present a physical model for the kinetics of porosity changes in arrays of viscous droplets and compare this with our experimental data. The combination of the physical model for the evolution of porosity with the scaling between porosity and permeability permits us to describe the evolution of permeability during densification. We anticipate that this will be a useful tool for predicting the longevity of degassing pathways in granular filled cracks, both in conduits and shallow lava domes, as well as during the sedimentation of exceptionally hot ignimbrites undergoing compaction and welding.

  14. A relative permeability modifier for water control of gas wells in a low-permeability reservoir

    SciTech Connect

    Chen Tielong; Zhao Yong; Peng Kezong; Pu Wanfeng

    1996-08-01

    Water control in gas wells is a major measure to enhance gas recovery. The work is concentrated on finding a highly selective polymer to reduce water production without affecting gas production from gas wells in low-permeability reservoirs. This paper presents the conceptions of residual resistance factors (RRF`s) to both wetting and non-wetting phases and the laboratory experimental and field trial results of relative permeability modifiers for water control in gas wells.

  15. Moisture Durability of Vapor Permeable Insulating Sheathing (Fact Sheet)

    SciTech Connect

    Not Available

    2013-10-01

    In this project, Building America team Building Science Corporation researched some of the ramifications of using exterior, vapor permeable insulation on retrofit walls with vapor permeable cavity insulation. Retrofit strategies are a key factor in reducing exterior building stock consumption.

  16. Permeability Changes in Reaction Induced Fracturing

    NASA Astrophysics Data System (ADS)

    Ulven, Ole Ivar; Malthe-Sørenssen, Anders; Kalia, Rajiv

    2013-04-01

    The process of fracture formation due to a volume increasing chemical reaction has been studied in a variety of different settings, e.g. weathering of dolerites by Røyne et al.[4], serpentinization and carbonation of peridotite by Rudge et al.[3] and replacement reactions in silica-poor igneous rocks by Jamtveit et al.[1]. It is generally assumed that fracture formation will increase the net permeability of the rock, and thus increase the reactant transport rate and subsequently the total reaction rate, as summarised by Kelemen et al.[2]. Røyne et al.[4] have shown that transport in fractures will have an effect on the fracture pattern formed. Understanding the feedback process between fracture formation and permeability changes is essential in assessing industrial scale CO2 sequestration in ultramafic rock, but little is seemingly known about how large the permeability change will be in reaction-induced fracturing under compression, and it remains an open question how sensitive a fracture pattern is to permeability changes. In this work, we study the permeability of fractures formed under compression, and we use a 2D discrete element model to study the fracture patterns and total reaction rates achieved with different permeabilities. We achieve an improved understanding of the feedback processes in reaction-driven fracturing, thus improving our ability to decide whether industrial scale CO2 sequestration in ultramafic rock is a viable option for long-term handling of CO2. References [1] Jamtveit, B, Putnis, C. V., and Malthe-Sørenssen, A., "Reaction induced fracturing during replacement processes," Contrib. Mineral Petrol. 157, 2009, pp. 127 - 133. [2] Kelemen, P., Matter, J., Streit, E. E., Rudge, J. F., Curry, W. B., and Blusztajn, J., "Rates and Mechanisms of Mineral Carbonation in Peridotite: Natural Processes and Recipes for Enhanced, in situ CO2 Capture and Storage," Annu. Rev. Earth Planet. Sci. 2011. 39:545-76. [3] Rudge, J. F., Kelemen, P. B., and

  17. Permeability-porosity relationships in sedimentary rocks

    USGS Publications Warehouse

    Nelson, Philip H.

    1994-01-01

    In many consolidated sandstone and carbonate formations, plots of core data show that the logarithm of permeability (k) is often linearly proportional to porosity (??). The slope, intercept, and degree of scatter of these log(k)-?? trends vary from formation to formation, and these variations are attributed to differences in initial grain size and sorting, diagenetic history, and compaction history. In unconsolidated sands, better sorting systematically increases both permeability and porosity. In sands and sandstones, an increase in gravel and coarse grain size content causes k to increase even while decreasing ??. Diagenetic minerals in the pore space of sandstones, such as cement and some clay types, tend to decrease log(k) proportionately as ?? decreases. Models to predict permeability from porosity and other measurable rock parameters fall into three classes based on either grain, surface area, or pore dimension considerations. (Models that directly incorporate well log measurements but have no particular theoretical underpinnings from a fourth class.) Grain-based models show permeability proportional to the square of grain size times porosity raised to (roughly) the fifth power, with grain sorting as an additional parameter. Surface-area models show permeability proportional to the inverse square of pore surface area times porosity raised to (roughly) the fourth power; measures of surface area include irreducible water saturation and nuclear magnetic resonance. Pore-dimension models show permeability proportional to the square of a pore dimension times porosity raised to a power of (roughly) two and produce curves of constant pore size that transgress the linear data trends on a log(k)-?? plot. The pore dimension is obtained from mercury injection measurements and is interpreted as the pore opening size of some interconnected fraction of the pore system. The linear log(k)-?? data trends cut the curves of constant pore size from the pore-dimension models

  18. Exploring the scale-dependent permeability of fractured andesite

    NASA Astrophysics Data System (ADS)

    Heap, Michael J.; Kennedy, Ben M.

    2016-08-01

    Extension fractures in volcanic systems exist on all scales, from microscopic fractures to large fissures. They play a fundamental role in the movement of fluids and distribution of pore pressure, and therefore exert considerable influence over volcanic eruption recurrence. We present here laboratory permeability measurements for porous (porosity = 0.03-0.6) andesites before (i.e., intact) and after failure in tension (i.e., the samples host a throughgoing tensile fracture). The permeability of the intact andesites increases with increasing porosity, from 2 ×10-17 to 5 ×10-11 m2. Following fracture formation, the permeability of the samples (the equivalent permeability) falls within a narrow range, 2- 6 ×10-11 m2, regardless of their initial porosity. However, laboratory measurements on fractured samples likely overestimate the equivalent permeability due to the inherent scale-dependence of permeability. To explore this scale-dependence, we first determined the permeability of the tensile fractures using a two-dimensional model that considers flow in parallel layers. Our calculations highlight that tensile fractures in low-porosity samples are more permeable (as high as 3.5 ×10-9 m2) than those in high-porosity samples (as low as 4.1 ×10-10 m2), a difference that can be explained by an increase in fracture tortuosity with porosity. We then use our fracture permeability data to model the equivalent permeability of fractured rock (with different host rock permeabilities, from 10-17 to 10-11 m2) with increasing lengthscale. We highlight that our modelling approach can be used to estimate the equivalent permeability of numerous scenarios at andesitic stratovolcanoes in which the fracture density and width and host rock porosity or permeability are known. The model shows that the equivalent permeability of fractured andesite depends heavily on the initial host rock permeability and the scale of interest. At a given lengthscale, the equivalent permeability of high-permeability

  19. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Permeability of spaces. 172.140 Section 172.140 Shipping... Subchapter O of This Chapter § 172.140 Permeability of spaces. (a) When doing the calculations required in § 172.130, the permeability of a floodable space other than a machinery space must be as listed in...

  20. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which...

  1. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Permeability of spaces. 172.185 Section 172.185 Shipping... Under Subchapter O of This Chapter § 172.185 Permeability of spaces. (a) When doing the calculations required in § 172.170, the permeability of a floodable space other than a machinery space must be as...

  2. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  3. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigid gas permeable contact lens. 886.5916 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn...

  4. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens. 886.5916 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5916 Rigid gas permeable contact lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn...

  5. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which...

  6. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  7. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which...

  8. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Permeability of spaces. 172.140 Section 172.140 Shipping... Subchapter O of This Chapter § 172.140 Permeability of spaces. (a) When doing the calculations required in § 172.130, the permeability of a floodable space other than a machinery space must be as listed in...

  9. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  10. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  11. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which...

  12. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Permeability of spaces. 172.185 Section 172.185 Shipping... Under Subchapter O of This Chapter § 172.185 Permeability of spaces. (a) When doing the calculations required in § 172.170, the permeability of a floodable space other than a machinery space must be as...

  13. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Permeability of spaces. 172.185 Section 172.185 Shipping... Under Subchapter O of This Chapter § 172.185 Permeability of spaces. (a) When doing the calculations required in § 172.170, the permeability of a floodable space other than a machinery space must be as...

  14. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Permeability of spaces. 172.140 Section 172.140 Shipping... Subchapter O of This Chapter § 172.140 Permeability of spaces. (a) When doing the calculations required in § 172.130, the permeability of a floodable space other than a machinery space must be as listed in...

  15. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  16. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Permeability of spaces. 172.185 Section 172.185 Shipping... Under Subchapter O of This Chapter § 172.185 Permeability of spaces. (a) When doing the calculations required in § 172.170, the permeability of a floodable space other than a machinery space must be as...

  17. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Permeability of spaces. 172.140 Section 172.140 Shipping... Subchapter O of This Chapter § 172.140 Permeability of spaces. (a) When doing the calculations required in § 172.130, the permeability of a floodable space other than a machinery space must be as listed in...

  18. Permeability of cork for water and ethanol.

    PubMed

    Fonseca, Ana Luisa; Brazinha, Carla; Pereira, Helena; Crespo, Joao G; Teodoro, Orlando M N D

    2013-10-01

    Transport properties of natural (noncompressed) cork were evaluated for water and ethanol in both vapor and liquid phases. The permeability for these permeants has been measured, as well as the sorption and diffusion coefficients. This paper focuses on the differences between the transport of gases' relevant vapors and their liquids (water and ethanol) through cork. A transport mechanism of vapors and liquids is proposed. Experimental evidence shows that both vapors and liquids permeate not only through the small channels across the cells (plasmodesmata), as in the permeation of gases, but also through the walls of cork cells by sorption and diffusion as in dense membranes. The present study also shows that cork permeability for gases was irreversibly and drastically decreased after cork samples were exposed to ethanol or water in liquid phase.

  19. Control of vascular permeability by adhesion molecules

    PubMed Central

    Sarelius, Ingrid H; Glading, Angela J

    2014-01-01

    Vascular permeability is a vital function of the circulatory system that is regulated in large part by the limited flux of solutes, water, and cells through the endothelial cell layer. One major pathway through this barrier is via the inter-endothelial junction, which is driven by the regulation of cadherin-based adhesions. The endothelium also forms attachments with surrounding proteins and cells via 2 classes of adhesion molecules, the integrins and IgCAMs. Integrins and IgCAMs propagate activation of multiple downstream signals that potentially impact cadherin adhesion. Here we discuss the known contributions of integrin and IgCAM signaling to the regulation of cadherin adhesion stability, endothelial barrier function, and vascular permeability. Emphasis is placed on known and prospective crosstalk signaling mechanisms between integrins, the IgCAMs- ICAM-1 and PECAM-1, and inter-endothelial cadherin adhesions, as potential strategic signaling nodes for multipartite regulation of cadherin adhesion. PMID:25838987

  20. Electrostatically gated membrane permeability in inorganic protocells.

    PubMed

    Li, Mei; Harbron, Rachel L; Weaver, Jonathan V M; Binks, Bernard P; Mann, Stephen

    2013-06-01

    Although several strategies are now available to produce functional microcompartments analogous to primitive cell-like structures, little progress has been made in generating protocell constructs with self-controlled membrane permeability. Here we describe the preparation of water-dispersible colloidosomes based on silica nanoparticles and delineated by a continuous semipermeable inorganic membrane capable of self-activated, electrostatically gated permeability. We use crosslinking and covalent grafting of a pH-responsive copolymer to generate an ultrathin elastic membrane that exhibits selective release and uptake of small molecules. This behaviour, which depends on the charge of the copolymer coronal layer, serves to trigger enzymatic dephosphorylation reactions specifically within the protocell aqueous interior. This system represents a step towards the design and construction of alternative types of artificial chemical cells and protocell models based on spontaneous processes of inorganic self-organization. PMID:23695636

  1. Control of vascular permeability by adhesion molecules.

    PubMed

    Sarelius, Ingrid H; Glading, Angela J

    2015-01-01

    Vascular permeability is a vital function of the circulatory system that is regulated in large part by the limited flux of solutes, water, and cells through the endothelial cell layer. One major pathway through this barrier is via the inter-endothelial junction, which is driven by the regulation of cadherin-based adhesions. The endothelium also forms attachments with surrounding proteins and cells via 2 classes of adhesion molecules, the integrins and IgCAMs. Integrins and IgCAMs propagate activation of multiple downstream signals that potentially impact cadherin adhesion. Here we discuss the known contributions of integrin and IgCAM signaling to the regulation of cadherin adhesion stability, endothelial barrier function, and vascular permeability. Emphasis is placed on known and prospective crosstalk signaling mechanisms between integrins, the IgCAMs- ICAM-1 and PECAM-1, and inter-endothelial cadherin adhesions, as potential strategic signaling nodes for multipartite regulation of cadherin adhesion. PMID:25838987

  2. Electrostatically gated membrane permeability in inorganic protocells

    NASA Astrophysics Data System (ADS)

    Li, Mei; Harbron, Rachel L.; Weaver, Jonathan V. M.; Binks, Bernard P.; Mann, Stephen

    2013-06-01

    Although several strategies are now available to produce functional microcompartments analogous to primitive cell-like structures, little progress has been made in generating protocell constructs with self-controlled membrane permeability. Here we describe the preparation of water-dispersible colloidosomes based on silica nanoparticles and delineated by a continuous semipermeable inorganic membrane capable of self-activated, electrostatically gated permeability. We use crosslinking and covalent grafting of a pH-responsive copolymer to generate an ultrathin elastic membrane that exhibits selective release and uptake of small molecules. This behaviour, which depends on the charge of the copolymer coronal layer, serves to trigger enzymatic dephosphorylation reactions specifically within the protocell aqueous interior. This system represents a step towards the design and construction of alternative types of artificial chemical cells and protocell models based on spontaneous processes of inorganic self-organization.

  3. Hydrogeologic modeling for permeable reactive barriers.

    PubMed

    Gupta, N; Fox, T C

    1999-08-12

    The permeable reactive barrier technology for in situ treatment of chlorinated solvents and other groundwater contaminants is becoming increasingly popular. Field scale implementation of this and other in situ technologies requires careful design based on the site-specific hydrogeology and contaminant plume characteristics. Groundwater flow modeling is an important tool in understanding the hydraulic behavior of the site and optimizing the reactive barrier design. A combination of groundwater flow modeling and particle tracking techniques was used to illustrate the effect of hydraulic conductivity of the aquifer and reactive media on key permeable barrier design parameters, such as the capture zone width, residence time, flow velocity, and discharge. Similar techniques were used to illustrate the modeling approach for design of different configurations of reactive barriers in homogeneous and heterogeneous settings.

  4. Enhancement of scleral macromolecular permeability with prostaglandins.

    PubMed Central

    Weinreb, R N

    2001-01-01

    PURPOSE: It is proposed that the sclera is a metabolically active and pharmacologically responsive tissue. These studies were undertaken to determine whether prostaglandin exposure can enhance scleral permeability to high-molecular-weight substances. METHODS: Topical prostaglandin F2 alpha (PGF2 alpha) was administered to monkeys to determine if this altered the amount of scleral matrix metalloproteinases (MMPs). Experiments also were performed to determine whether the prostaglandin F (FP) receptor and gene transcripts are expressed in normal human sclera. Permeability of organ-cultured human sclera following prostaglandin exposure then was studied and the amount of MMP released into the medium measured. Finally, the permeability of human sclera to basic fibroblast growth factor (FGF-2) was determined following prostaglandin exposure. RESULTS: Topical prostaglandin administration that reduced scleral collagen also increased scleral MMP-1, MMP-2, and MMP-3 by 63 +/- 35%, 267 +/- 210%, and 729 +/- 500%, respectively. FP receptor protein was localized in scleral fibroblasts, and FP receptor gene transcript was identified in sclera. Exposure to prostaglandin F2 alpha, 17-phenyltrinor, PGF2 alpha, or latanoprost acid increased scleral permeability by up to 124%, 183%, or 213%, respectively. In these cultures, MMP-1, MMP-2, and MMP-3 were increased by up to 37%, 267%, and 96%, respectively. Finally, transscleral absorption of FGF-2 was increased by up to 126% with scleral exposure to latanoprost. CONCLUSIONS: These studies demonstrate that the sclera is metabolically active and pharmacologically responsive to prostaglandins. Further, they demonstrate the feasibility of cotreatment with prostaglandin to enhance transscleral delivery of peptides, such as growth factors and high-molecular-weight substances, to the posterior segment of the eye. PMID:11797317

  5. Permeability of self-affine rough fractures

    PubMed

    Drazer; Koplik

    2000-12-01

    The permeability of two-dimensional fractures with self-affine fractal roughness is studied via analytic arguments and numerical simulations. The limit where the roughness amplitude is small compared with average fracture aperture is analyzed by a perturbation method, while in the opposite case of narrow aperture, we use heuristic arguments based on lubrication theory. Numerical simulations, using the lattice Boltzmann method, are used to examine the complete range of aperture sizes, and confirm the analytic arguments. PMID:11138092

  6. Methods of determining permeability, transmissibility and drawdown

    USGS Publications Warehouse

    Bentall, Ray

    1964-01-01

    If the Theis graphical method is used for determining the hydraulic constants of an aquifer under water-table conditions, the observed drawdowns should be corrected for the decrease in saturated thickness. This is especially true if the drawdown is a large fraction of the original saturated thickness, for then the computed coefficient of permeability is highly inaccurate if based on observed, rather than corrected, water levels. Wenzel's limiting formula, a modification of the Theis graphical method, is useful where u=r2s/4Tt is less than about 0.01. However, a shorter procedure for determination of the coefficient of transmissibility, as well as the coefficient of storage, consists of plotting the values of the corrected drawdowns against the values of the logarithm of r. Wenzel (1942) suggested that observation wells be situated on lines that extend upgradient and downgradient from the pumped well. However, a detailed analysis of aquifer-test results indicates that such a restriction is unnecessary. The gradient method for determining permeability should yield the same results as the Thies method. The former, when applied for a distance within the range of applicability of the latter, is merely a duplication of effort or, at best, a crude check. Because of the limitations of accuracy in plotting, the gradient method is much less satisfactory. That Wenzel (1942) obtained identical results from the two methods is regarded as a coincidence. Failure to take into consideration the fact that the pumped well does not tap the full thickness of the aquifer leads to an apparent coefficient of permeability that is much too low, especially if the aquifer consists of stratified sediments. The average coefficient of permeability computed from uncorrected drawdowns may be only a little more than half of the true value.

  7. Nonlinear effective pressure law for permeability

    NASA Astrophysics Data System (ADS)

    Li, M.; Xiao, W.-L.; Bernabé, Y.; Zhao, J.-Z.

    2014-01-01

    The permeability k of porous rocks is known to vary with confining pressure pc and pore fluid pressure pf. But it is, in principle, possible to replace the two-variable function k(pf, pc) by a function k(peff) of a single variable, peff(pf, pc), called the effective pressure. Our goal in this paper is to establish an experimental method for determining a possibly nonlinear, effective pressure law (EPL) for permeability, i.e., find the function κs(pf, pc) such that the effective pressure is given by peff = pc - κs(pf, pc) pf. We applied this method to a set of 26 sandstone cores from various hydrocarbon reservoirs in China. We found that κs greatly varied, from sample to sample, in magnitude and range, sometimes even reaching theoretically prohibited values (i.e., greater than 1 or lower than porosity). One interesting feature of κs(pf, pc) is that it could be approximately described in all rocks but one as a decreasing function κs(pc - pf) of Terzaghi's differential pressure. We also investigated the dependence of permeability on peff for each of our samples. Three models from the literature, i.e., exponential (E), power law (P), and the Walsh model (W), were tested. The (W) model was more likely to fit the experimental data of cores with a high pressure dependence of permeability whereas (E) occurred more frequently in low-pressure-sensitive rocks. Finally, we made various types of two- and three-dimensional microstructural observations that generally supported the trend mentioned above.

  8. Nonequilibrium gas absorption in rotating permeable media

    NASA Astrophysics Data System (ADS)

    Baev, V. K.; Bazhaikin, A. N.

    2016-08-01

    The absorption of ammonia, sulfur dioxide, and carbon dioxide by water and aqueous solutions in rotating permeable media, a cellular porous disk, and a set of spaced-apart thin disks has been considered. The efficiency of cleaning air to remove these impurities is determined, and their anomalously high solubility (higher than equilibrium value) has been discovered. The results demonstrate the feasibility of designing cheap efficient rotor-type absorbers to clean gases of harmful impurities.

  9. Anisotropic Hydraulic Permeability Under Finite Deformation

    PubMed Central

    Ateshian, Gerard A.; Weiss, Jeffrey A.

    2011-01-01

    The structural organization of biological tissues and cells often produces anisotropic transport properties. These tissues may also undergo large deformations under normal function, potentially inducing further anisotropy. A general framework for formulating constitutive relations for anisotropic transport properties under finite deformation is lacking in the literature. This study presents an approach based on representation theorems for symmetric tensor-valued functions and provides conditions to enforce positive semi-definiteness of the permeability or diffusivity tensor. Formulations are presented which describe materials that are orthotropic, transversely isotropic, or isotropic in the reference state, and where large strains induce greater anisotropy. Strain-induced anisotropy of the permeability of a solid-fluid mixture is illustrated for finite torsion of a cylinder subjected to axial permeation. It is shown that, in general, torsion can produce a helical flow pattern, rather than the rectilinear pattern observed when adopting a more specialized, unconditionally isotropic spatial permeability tensor commonly used in biomechanics. The general formulation presented in this study can produce both affine and non-affine reorientation of the preferred directions of material symmetry with strain, depending on the choice of material functions. This study addresses a need in the biomechanics literature by providing guidelines and formulations for anisotropic strain-dependent transport properties in porous-deformable media undergoing large deformations. PMID:21034145

  10. Porosity and Permeability of Chondritic Materials

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Corrigan, Catherine M.; Dahl, Jason; Long, Michael

    1996-01-01

    We have investigated the porosity of a large number of chondritic interplanetary dust particles and meteorites by three techniques: standard liquid/gas flow techniques, a new, non-invasive ultrasonic technique, and image processing of backscattered images . The latter technique is obviously best suited to sub-kg sized samples. We have also measured the gas and liquid permeabilities of some chondrites by two techniques: standard liquid/gas flow techniques, and a new, non-destructive pressure release technique. We find that chondritic IDP's have a somewhat bimodal porosity distribution. Peaks are present at 0 and 4% porosity; a tail then extends to 53%. These values suggest IDP bulk densities of 1.1 to 3.3 g/cc. Type 1-3 chondrite matrix porosities range up to 30%, with a peak at 2%. The bulk porosities for type 1-3 chondrites have the same approximate range as exhibited by matrix, indicating that other components of the bulk meteorites (including chondrules and aggregates) have the same average porosity as matrix. These results reveal that the porosity of primitive materials at scales ranging from nanogram to kilogram are similar, implying similar accretion dynamics operated through 12 orders of size magnitude. Permeabilities of the investigated chondrites vary by several orders of magnitude, and there appears to be no simple dependence of permeability with degree of aqueous alteration, or chondrite type.

  11. Atrial natriuretic factor increases vascular permeability

    NASA Technical Reports Server (NTRS)

    Lockette, Warren; Brennaman, Bruce

    1990-01-01

    An increase in central blood volume in microgravity may result in increased plasma levels of atrial natriuretic factor (ANF). In this study, it was determined whether ANF increases capillary permeability to plasma protein. Conscious, bilaterally nephrectomized male rats were infused with either saline, ANF + saline, or hexamethonium + saline over 2 h following bolus injections of (I-125)-albumin and (C-14)-dextran of similar molecular size. Blood pressure was monitored, and serial determinations of hematocrits were made. Animals infused with 1.0 microg/kg per min ANF had significantly higher hematocrits than animals infused with saline vehicle. Infusion of ANF increased the extravasation of (I-125)-albumin, but not (C-14)-dextran from the intravascular compartment. ANF also induced a depressor response in rats, but the change in blood pressure did not account for changes in capillary permeability to albumin; similar depressor responses induced by hexamethonium were not accompanied by increased extravasation of albumin from the intravascular compartment. ANF may decrease plasma volume by increasing permeability to albumin, and this effect of ANF may account for some of the signs and symptoms of space motion sickness.

  12. Atrial natriuretic factor increases vascular permeability

    SciTech Connect

    Lockette, W.; Brennaman, B. )

    1990-12-01

    An increase in central blood volume in microgravity may result in increased plasma levels of atrial natriuretic factor (ANF). Since elevations in plasma ANF are found in clinical syndromes associated with edema, and since space motion sickness induced by microgravity is associated with an increase in central blood volume and facial edema, we determined whether ANF increases capillary permeability to plasma protein. Conscious, bilaterally nephrectomized male rats were infused with either saline, ANF + saline, or hexamethonium + saline over 2 h following bolus injections of 125I-albumin and 14C-dextran of similar molecular size. Blood pressure was monitored and serial determinations of hematocrits were made. Animals infused with 1.0 micrograms.kg-1.min-1 ANF had significantly higher hematocrits than animals infused with saline vehicle. Infusion of ANF increased the extravasation of 125I-albumin, but not 14C-dextran from the intravascular compartment. ANF also induced a depressor response in rats, but the change in blood pressure did not account for changes in capillary permeability to albumin; similar depressor responses induced by hexamethonium were not accompanied by increased extravasation of albumin from the intravascular compartment. ANF may decrease plasma volume by increasing permeability to albumin, and this effect of ANF may account for some of the signs and symptoms of space motion sickness.

  13. Gravity filtration of suspensions: permeability effects

    NASA Astrophysics Data System (ADS)

    Soori, Tejaswi; Wang, Mengyu; Ward, Thomas

    2015-11-01

    This paper examines the filtration rates of mono-modal suspensions as a function of time and a cake layer builds up through theory and experimentation. Darcy's Law, which describes fluid flow through porous media, was applied along with the Kynch theory of sedimentation, which provides the basis for analyzing low concentration (ϕ <=20%) cake formation. Experiments were performed to study the effects of varying particle sizes (45 μm <= d <= 1400 μm) and total solid concentration ϕ on both the formation rate of the cake layer and its flow permeability (k) in conjunction with the filter media. A CCD camera was used to capture images of the cake formation and fluid drainage processes, and subsequent image and theoretical analysis found the fluid flow experienced a constant pressure loss due to the permeability of the filter media, whereas the experienced pressure loss due to the cake formation varies as a function of time, ϕ and d. The rate of cake formation was also found to be independent of ϕ but dependent on d which can be attributed to a change in porosity affecting permeability. Studies on similar systems with multi-modal suspensions are in-progress.

  14. Effect of water on hydrogen permeability

    NASA Technical Reports Server (NTRS)

    Hulligan, David; Tomazic, William A.

    1987-01-01

    Doping of hydrogen with CO and CO2 was developed to reduce hydrogen permeation in Stirling engines by forming a low permeability oxide coating on the inner surface of the heater head tubes. Although doping worked well, under certain circumstances the protective oxide could be chemically reduced by the hydrogen in the engine. Some oxygen is required in the hydrogen to prevent reduction. Eventually, all the oxygen in the hydrogen gas - whatever its source - shows up as water. This is the result of hydrogen reducing the CO, CO2, or the protective inner surface oxides. This water can condense in the engine system under the right conditions. If the concentration of water vapor is reduced to a low enough level, the hydrogen can chemically reduce the oxide coating, resulting in an increase in permeability. This work was done to define the minimum water content required to avoid this reduction in the oxide coating. The results of this testing show that a minimum of approximately 750 ppm water is required to prevent an increase in permeability of CG-27, a high temperature metal alloy selected for Stirling engine heater tubes.

  15. Endothelial cell permeability to water and antipyrine

    SciTech Connect

    Garrick, R.A.

    1986-03-05

    The endothelium provides a structural barrier between plasma constituents and the tissues. The permeability characteristics of the the endothelial cells regulate the transcellular movement of materials across this barrier while other movement is paracellular. In this study the permeability of the endothelial cells to tritiated water (/sup 3/HHO) and /sup 14/C-labeled antipyrine (AP) was investigated. The cells were isolated non-enzymatically from calf pulmonary artery and were maintained in culture and used between the seventh and fifteenth passage. The cells were removed from the T-flasks with a rubber policeman, titurated with a 22g needle and centrifuged. The cells were mixed with an extracellular marker, drawn into polyethylene tubing and packed by centrifugation for use in the linear diffusion technique. All measurements were made at 37 C. The diffusion coefficients for /sup 3/HHO through the packed cells (D), the intracellular material (D/sub 2/), and the extracellular material (D/sub 1/) were 0.682, 0.932 and 2.45 x 10/sup -5/ cm/sup 2/ s/sup -1/ and for AP were 0.273, 0.355 and 1.13 x 10/sup -5/ cm/sup 2/ s/sup -1/ respectively. The permeability coefficient calculated by the series-parallel pathway model for /sup 3/HHO was higher than that for AP and for both /sup 3/HHO and AP were lower than those calculated for isolated lung cells and erythrocytes.

  16. Changes in rock salt permeability due to nearby excavation

    SciTech Connect

    Stormont, J C; Howard, C L

    1991-07-01

    Changes in brine and gas permeability of rock salt as a result of nearby excavation (mine-by) have been measured from the underground workings of the WIPP facility. Prior to the mine-by, the formation responds as a porous medium with a very low brine permeability, a significant pore (brine) pressure and no measurable gas permeability. The mine-by excavation creates a dilated, partially saturated zone in the immediate vicinity of the excavation with an increased permeability to brine and a measurable permeability to gas. The changes in hydrologic properties are discussed in the context of pore structure changes.

  17. Evaluating Permeability Enchancement Using Electrical Techniques

    SciTech Connect

    John W. Pritchett

    2008-09-01

    Enhanced Geothermal Systems (EGS) development projects involve the artificial stimulation of relatively impermeable high-temperature underground regions (at depths of 2-4 kilometers or more) to create sufficient permeability to permit underground fluid circulation, so that hot water can be withdrawn from production wells and used to generate electric power. Several major research projects of this general type have been undertaken in the past in New Mexico (Fenton Hill), Europe, Japan and Australia. Recent U.S. activities along these lines focus mainly on stimulating peripheral areas of existing operating hydrothermal fields rather than on fresh 'greenfield' sites, but the long-term objective of the Department of Energy's EGS program is the development of large-scale power projects based on EGS technology (MIT, 2006; NREL, 2008). Usually, stimulation is accomplished by injecting water into a well at high pressure, enhancing permeability by the creation and propagation of fractures in the surrounding rock (a process known as 'hydrofracturing'). Beyond just a motivation, low initial system permeability is also an essential prerequisite to hydrofracturing. If the formation permeability is too high, excessive fluid losses will preclude the buildup of sufficient pressure to fracture rock. In practical situations, the actual result of injection is frequently to re-open pre-existing hydrothermally-mineralized fractures, rather than to create completely new fractures by rupturing intact rock. Pre-existing fractures can often be opened using injection pressures in the range 5-20 MPa. Creation of completely new fractures will usually require pressures that are several times higher. It is preferable to undertake development projects of this type in regions where tectonic conditions are conducive to shear failure, so that when pre-existing fractures are pressurized they will fail by shearing laterally. If this happens, the fracture will often stay open afterwards even if

  18. Permeability Evolution of Granite Gneiss During Triaxial Creep Tests

    NASA Astrophysics Data System (ADS)

    Liu, L.; Xu, W. Y.; Wang, H. L.; Wang, W.; Wang, R. B.

    2016-09-01

    Permeability is an important factor for seepage analysis of rock material, and a key factor in ensuring the safety of underground works. In this study, the permeability evolution of granite gneiss during triaxial creep tests was investigated. In the context of an underground oil storage cavern in China, a series of hydro-mechanical coupling creep tests were conducted on rock cores of granite gneiss at three different pore pressures to reveal the effect of pore pressure on the permeability evolution and to investigate the correlation between the permeability and volumetric strain during the creep process. During the creep tests, the permeability decreases in the initial loading phase. At all deviatoric stress levels, the permeability remains stable in the steady creep stage and increases rapidly in the accelerated creep stage. Based on the test data, the initial permeability, steady permeability and peak permeability at various stress levels are defined. The effect of pore pressure on the permeability is captured by a linear model. In addition, the relationship between permeability and volumetric strain can be described as a process divided into three phases, with different functions in each phase.

  19. Assessing the potential for restoration of surface permeability for permeable pavements through maintenance.

    PubMed

    Drake, Jennifer; Bradford, Andrea

    2013-01-01

    Permeable pavements (PPs) have been in use as stormwater management systems in Canada and the United States for over 20 years. After years of exposure to sediment and debris build-up, surface clogging reduces the infiltration of stormwater and inhibits the hydraulic and environmental functions of the pavement. Removal of surface material has been shown to restore infiltration but the majority of studies have been limited to small-scale testing. This paper presents the results of small- and full-sized equipment testing aimed at restoring surface permeability, including the first testing of regenerative-air and vacuum-sweeping streetsweepers in Ontario. Maintenance achieved partial restoration of PP surface permeability. Post-treatment surface infiltration rates displayed large spatial variability, highlighting that localized conditions throughout the pavement have a confounding influence on the overall effectiveness of maintenance. The impact of maintenance may be improved by establishing regular cleaning intervals and developing instructional guidelines for pavement owners and equipment operators.

  20. Permeability-porosity relationships of subduction zone sediments

    USGS Publications Warehouse

    Gamage, K.; Screaton, E.; Bekins, B.; Aiello, I.

    2011-01-01

    Permeability-porosity relationships for sediments from the northern Barbados, Costa Rica, Nankai, and Peru subduction zones were examined based on sediment type, grain size distribution, and general mechanical and chemical compaction history. Greater correlation was observed between permeability and porosity in siliciclastic sediments, diatom oozes, and nannofossil chalks than in nannofossil oozes. For siliciclastic sediments, grouping of sediments by percentage of clay-sized material yields relationships that are generally consistent with results from other marine settings and suggests decreasing permeability as percentage of clay-sized material increases. Correction of measured porosities for smectite content improved the correlation of permeability-porosity relationships for siliciclastic sediments and diatom oozes. The relationship between permeability and porosity for diatom oozes is very similar to the relationship in siliciclastic sediments, and permeabilities of both sediment types are related to the amount of clay-size particles. In contrast, nannofossil oozes have higher permeability values by 1.5 orders of magnitude than siliciclastic sediments of the same porosity and show poor correlation between permeability and porosity. More indurated calcareous sediments, nannofossil chalks, overlap siliciclastic permeabilities at the lower end of their measured permeability range, suggesting similar consolidation patterns at depth. Thus, the lack of correlation between permeability and porosity for nannofossil oozes is likely related to variations in mechanical and chemical compaction at shallow depths. This study provides the foundation for a much-needed global database with fundamental properties that relate to permeability in marine settings. Further progress in delineating controls on permeability requires additional carefully documented permeability measurements on well-characterized samples. ?? 2010 Elsevier B.V.

  1. Permeability development during compaction of pumiceous dome lavas: testing the permeable foam collapse model

    NASA Astrophysics Data System (ADS)

    Ashwell, P.; Kendrick, J. E.; Lavallee, Y.; kennedy, B.; Hess, K.; von Aulock, F. W.; Cole, J. W.; Dingwell, D. B.

    2011-12-01

    The evolution of the porous network during lava dome extrusions is commonly perceived as the key control on the permeability which regulates the pore pressure, thereby challenging the stability of the dome. Here, we present experimental results of porosity and permeability evolution during compaction of aphiric and crystal-bearing rhyolitic, pumiceous (porosity ~60 %) lavas from Tarawera and Ngongotaha volcanoes (Taupo Volcanic Zone, New Zealand), respectively. The The Ngongotaha sample is from the crystal-free dome carapace (erupted ~200 ka following caldera collapse at Rotorua Caldera), while the Tarawera sample is a crystalline, pumiceous clast from a dome-collapse generated block and ash flow (at Okataina Caldera ~1314 AD). This study tests the validity of the 'permeable foam' model by comparing properties of the experimentally compacted pumice to denser material seen in the exposed cores of Tarawera and Ngongotaha. Cylindrical samples were deformed under an axial stress of 2.8 MPa at 650-750°C (above their calorimetric glass transition temperature) up a total axial strain of 50 %. The porosity and permeability of the samples were characterized at strain increments of 10 %. The samples exhibit strain hardening during compaction. A rapid reduction in permeability along the primary axis occurs during the initial stage of compression and continues to decrease with increasing strain and densification of the lava. Development of permeability of each lava differs as the crystallinity affects the compaction process. The development of textures and microstructures is characterised using petrographic analysis and neutron computed tomography. The findings from the study are then put into the context of lava dome growth at Tarawera and Ngongotaha volcanoes.

  2. Hydraulic tests in highly permeable aquifers

    USGS Publications Warehouse

    Butler, J.J.; Zhan, X.

    2004-01-01

    A semianalytical solution is presented for a mathematical model describing the flow of groundwater in response to a slug or pumping test in a highly permeable, confined aquifer. This solution, which is appropriate for wells of any degree of penetration and incorporates inertial mechanisms at both the test and observation wells, can be used to gain new insights into hydraulic tests in highly permeable settings. The oscillatory character of slug- and pumping-induced responses will vary considerably across a site, even in an essentially homogeneous formation, when wells of different radii, depths, and screen lengths are used. Thus variations in the oscillatory character of responses do not necessarily indicate variations in hydraulic conductivity (K). Existing models for slug tests in partially penetrating wells in high-K aquifers neglect the storage properties of the media. That assumption, however, appears reasonable for a wide range of common conditions. Unlike in less permeable formations, drawdown at an observation well in a high-K aquifer will be affected by head losses in the pumping well. Those losses, which affect the form of the pumping-induced oscillations, can be difficult to characterize. Thus analyses of observation-well drawdown should utilize data from the period after the oscillations have dissipated whenever possible. Although inertial mechanisms can have a large impact on early-time drawdown, that impact decreases rapidly with duration of pumping and distance to the observation well. Conventional methods that do not consider inertial mechanisms should therefore be viable options for the analysis of drawdown data at moderate to large times.

  3. Engineered Trehalose Permeable to Mammalian Cells

    PubMed Central

    Abazari, Alireza; Meimetis, Labros G.; Budin, Ghyslain; Bale, Shyam Sundhar; Weissleder, Ralph; Toner, Mehmet

    2015-01-01

    Trehalose is a naturally occurring disaccharide which is associated with extraordinary stress-tolerance capacity in certain species of unicellular and multicellular organisms. In mammalian cells, presence of intra- and extracellular trehalose has been shown to confer improved tolerance against freezing and desiccation. Since mammalian cells do not synthesize nor import trehalose, the development of novel methods for efficient intracellular delivery of trehalose has been an ongoing investigation. Herein, we studied the membrane permeability of engineered lipophilic derivatives of trehalose. Trehalose conjugated with 6 acetyl groups (trehalose hexaacetate or 6-O-Ac-Tre) demonstrated superior permeability in rat hepatocytes compared with regular trehalose, trehalose diacetate (2-O-Ac-Tre) and trehalose tetraacetate (4-O-Ac-Tre). Once in the cell, intracellular esterases hydrolyzed the 6-O-Ac-Tre molecules, releasing free trehalose into the cytoplasm. The total concentration of intracellular trehalose (plus acetylated variants) reached as high as 10 fold the extracellular concentration of 6-O-Ac-Tre, attaining concentrations suitable for applications in biopreservation. To describe this accumulation phenomenon, a diffusion-reaction model was proposed and the permeability and reaction kinetics of 6-O-Ac-Tre were determined by fitting to experimental data. Further studies suggested that the impact of the loading and the presence of intracellular trehalose on cellular viability and function were negligible. Engineering of trehalose chemical structure rather than manipulating the cell, is an innocuous, cell-friendly method for trehalose delivery, with demonstrated potential for trehalose loading in different types of cells and cell lines, and can facilitate the wide-spread application of trehalose as an intracellular protective agent in biopreservation studies. PMID:26115179

  4. Evaluation of permeable fractures in rock aquifers

    NASA Astrophysics Data System (ADS)

    Bok Lee, Hang

    2015-04-01

    In this study, the practical usefulness and fundamental applicability of a self-potential (SP) method for identifying the permeable fractures were evaluated by a comparison of SP methods with other geophysical logging methods and hydraulic tests. At a 10 m-shallow borehole in the study site, the candidates of permeable fractures crossing the borehole were first determined by conventional geophysical methods such as an acoustic borehole televiwer, temperature, electrical conductivity and gamma-gamma loggings, which was compared to the analysis by the SP method. Constant pressure injection and recovery tests were conducted for verification of the hydraulic properties of the fractures identified by various logging methods. The acoustic borehole televiwer and gamma-gamma loggings detected the open space or weathering zone within the borehole, but they cannot prove the possibility of a groundwater flow through the detected fractures. The temperature and electrical conductivity loggings had limitations to detect the fractured zones where groundwater in the borehole flows out to the surrounding rock aquifers. Comparison of results from different methods showed that there is a best correlation between the distribution of hydraulic conductivity and the variation of the SP signals, and the SP logging can estimate accurately the hydraulic activity as well as the location of permeable fractures. Based on the results, the SP method is recommended for determining the hydraulically-active fractures rather than other conventional geophysical loggings. This self-potential method can be effectively applied in the initial stage of a site investigation which selects the optimal location and evaluates the hydrogeological property of fractures in target sites for the underground structure including the geothermal reservoir and radioactive waste disposal.

  5. The kinetics of denitrification in permeable sediments

    NASA Astrophysics Data System (ADS)

    Evrard, Victor; Glud, Ronnie N.; Cook, Perran L. M.

    2013-04-01

    Permeable sediments comprise the majority of shelf sediments, yet the rates of denitrification remain highly uncertain in these environments. Computational models are increasingly being used to understand the dynamics of denitrification in permeable sediments, which are complex environments to study experimentally. The realistic implementation of such models requires reliable experimentally derived data on the kinetics of denitrification. Here we undertook measurements of denitrification kinetics as a function of nitrate concentration and in the presence and absence of oxygen, in carefully controlled flow through reactor experiments on sediments taken from six shallow coastal sites in Port Phillip Bay, Victoria, Australia. The results showed that denitrification commenced rapidly (within 30 min) after the onset of anoxia and the kinetics could be well described by Michaelis-Menten kinetics with half saturation constants (apparent Km) ranging between 1.5 and 19.8 μM, and maximum denitrification rate (Vmax) were in the range of 0.9-7.5 nmol mL-1 h-1. The production of N2 through anaerobic ammonium oxidation (anammox) was generally found to be less than 10% that of denitrification. Vmax were in the same range as previously reported in cohesive sediments despite organic carbon contents one order of magnitude lower for the sediments studied here. The ratio of sediment O2 consumption to Vmax was in the range of 0.02-0.09, and was on average much lower than the theoretical ratio of 0.8. The most likely explanation for this is that the microbial community is not able to instantaneously shift or optimally use a particular electron acceptor in the highly dynamic redox environment experienced in permeable sediments. Consistent with this explanation, subsequent longer-term experiments over 5 days showed that denitrification rates increased by a factor of 10 within 3 days of the permanent onset of anoxia. In contrast to previous studies, we did not observe any significant

  6. Osmotic water permeability of human red cells

    SciTech Connect

    Terwilliger, T.C.; Solomon, A.K.

    1981-05-01

    The osmotic water permeability of human red cells has been reexamined with a stopped-flow device and a new perturbation technique. Small osmotic gradients are used to minimize the systematic error caused by nonlinearities in the relationship between cell volume and light scattering. Corrections are then made for residual systematic error. Our results show that the hydraulic conductivity, Lp, is essentially independent of the direction of water flow and of osmolality in the range 184-365 mosM. the mean value of Lp obtained obtained was 1.8 +/- 0.1 (SEM) X 10-11 cm3 dyne -1 s-1.

  7. Gas permeable electrode for electrochemical system

    DOEpatents

    Ludwig, Frank A.; Townsend, Carl W.

    1989-01-01

    An electrode apparatus adapted for use in electrochemical systems having an anode compartment and a cathode compartment in which gas and ions are produced and consumed in the compartments during generation of electrical current. The electrode apparatus includes a membrane for separating the anode compartment from the cathode compartment wherein the membrane is permeable to both ions and gas. The cathode and anode for the assembly are provided on opposite sides of the membrane. During use of the membrane-electrode apparatus in electrochemical cells, the gas and ions generated at the cathode or anode migrate through the membrane to provide efficient transfer of gas and ions between the anode and cathode compartments.

  8. Nerve impulses increase glial intercellular permeability.

    PubMed

    Marrero, H; Orkand, R K

    1996-03-01

    Coordinating the activity of neurons and their satellite glial cells requires mechanisms by which glial cells detect neuronal activity and change their properties as a result. This study monitors the intercellular diffusion of the fluorescent dye Lucifer Yellow (LY), following its injection into glial cells of the frog optic nerve, and demonstrates that nerve impulses increase the permeability of interglial gap junctions. Consequently, the spatial buffer capacity of the neuroglial cell syncytium for potassium, other ions, and small molecules will be enhanced; this may facilitate glial function in maintaining homeostasis of the neuronal microenvironment. PMID:8833199

  9. PERMEABILITY OF SALTSTONE MEASUREMENT BY BEAM BENDING

    SciTech Connect

    Harbour, J; Tommy Edwards, T; Vickie Williams, V

    2008-01-30

    One of the goals of the Saltstone variability study is to identify (and, quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. A performance property for Saltstone mixes that is important but not routinely measured is the liquid permeability or saturated hydraulic conductivity of the cured Saltstone mix. The value for the saturated hydraulic conductivity is an input into the Performance Assessment for the SRS Z-Area vaults. Therefore, it is important to have a method available that allows for an accurate and reproducible measurement of permeability quickly and inexpensively. One such method that could potentially meet these requirements for the measurement of saturated hydraulic conductivity is the technique of beam bending, developed by Professor George Scherer at Princeton University. In order to determine the feasibility of this technique for Saltstone mixes, a summer student, David Feliciano, was hired to work at Princeton under the direction of George Scherer. This report details the results of this study which demonstrated the feasibility and applicability of the beam bending method to measurement of permeability of Saltstone samples. This research effort used samples made at Princeton from a Modular Caustic side solvent extraction Unit based simulant (MCU) and premix at a water to premix ratio of 0.60. The saturated hydraulic conductivities for these mixes were measured by the beam bending technique and the values determined were of the order of 1.4 to 3.4 x 10{sup -9} cm/sec. These values of hydraulic conductivity are consistent with independently measured values of this property on similar MCU based mixes by Dixon and Phifer. These values are also consistent with the hydraulic conductivity of a generic Saltstone mix measured by Langton in 1985. The high water to premix ratio used for Saltstone along with the relatively low degree of hydration for

  10. Novel insights into the mitochondrial permeability transition

    PubMed Central

    Bonora, Massimo; Bravo-San Pedro, José Manuel; Kroemer, Guido; Galluzzi, Lorenzo; Pinton, Paolo

    2014-01-01

    Alavian and colleagues recently provided further evidence in support of the notion that the c subunit of the mitochondrial F1FO ATP synthase constitutes the long-sought pore-forming unit of the supramolecular complex responsible for the so-called ‘mitochondrial permeability transition’ (MPT). Besides shedding new light on the molecular mechanisms that underlie the MPT, these findings corroborate the notion that several components of the cell death machinery, including cytochrome c and the F1FO ATP synthase, mediate critical metabolic activities. PMID:25486353

  11. On the dynamic viscous permeability tensor symmetry.

    PubMed

    Perrot, Camille; Chevillotte, Fabien; Panneton, Raymond; Allard, Jean-François; Lafarge, Denis

    2008-10-01

    Based on a direct generalization of a proof given by Torquato for symmetry property in static regime, this express letter clarifies the reasons why the dynamic permeability tensor is symmetric for spatially periodic structures having symmetrical axes which do not coincide with orthogonal pairs being perpendicular to the axis of three-, four-, and sixfold symmetry. This somewhat nonintuitive property is illustrated by providing detailed numerical examples for a hexagonal lattice of solid cylinders in the asymptotic and frequency dependent regimes. It may be practically useful for numerical implementation validation and/or convergence assessment.

  12. Gas permeability measurements for film envelope materials

    DOEpatents

    Ludtka, G.M.; Kollie, T.G.; Watkin, D.C.; Walton, D.G.

    1998-05-12

    Method and apparatus for measuring the permeability of polymer film materials such as used in super-insulation powder-filled evacuated panels (PEPs) reduce the time required for testing from several years to weeks or months. The method involves substitution of a solid non-outgassing body having a free volume of between 0% and 25% of its total volume for the usual powder in the PEP to control the free volume of the ``body-filled panel.`` Pressure versus time data for the test piece permit extrapolation to obtain long term performance of the candidate materials. 4 figs.

  13. Gas permeability measurements for film envelope materials

    DOEpatents

    Ludtka, Gerard M.; Kollie, Thomas G.; Watkin, David C.; Walton, David G.

    1998-01-01

    Method and apparatus for measuring the permeability of polymer film materials such as used in super-insulation powder-filled evacuated panels (PEPs) reduce the time required for testing from several years to weeks or months. The method involves substitution of a solid non-outgassing body having a free volume of between 0% and 25% of its total volume for the usual powder in the PEP to control the free volume of the "body-filled panel". Pressure versus time data for the test piece permit extrapolation to obtain long term performance of the candidate materials.

  14. The effect of concanavalin A and wheat germ agglutinin on the ultrastructure and permeability of rat intestine. A possible model for an intestinal allergic reaction.

    PubMed

    Sjölander, A; Magnusson, K E; Latkovic, S

    1984-01-01

    Sprague-Dawley rats were exposed to lectins, either concanavalin A (Con A) or wheat germ agglutinin (WGA). The lectins were instilled into a ligated segment of the distal small intestine together with permeability markers, fluoresceinated dextran (MW 3,000) or a mixture of differently sized polyethylene glycols (MW 400, 600 and 1,000). WGA-treated rats showed a decreased permeability to small molecules (MW less than 600) of polyethylene glycol but an increase for a larger dextran molecule (MW 3,000). These effects as well as the morphological findings might mimic the situation in patients with food allergy or celiac disease. Con A-treated rats had decreased intestinal permeability to the larger dextran molecules (MW 3,000), whereas the passage of small molecules was unaffected and the ultrastructural effects were minute. The Con A-induced changes could result from a mucotractive effect, associated with a low-grade gut allergy. These observations suggest that lectins can affect both the ultrastructure and the permeability of the intestine, in a way assumed to mimic allergic reactions to food constituents.

  15. Antibiotic Treatment Affects Intestinal Permeability and Gut Microbial Composition in Wistar Rats Dependent on Antibiotic Class

    PubMed Central

    Tulstrup, Monica Vera-Lise; Christensen, Ellen Gerd; Carvalho, Vera; Linninge, Caroline; Ahrné, Siv; Højberg, Ole; Licht, Tine Rask; Bahl, Martin Iain

    2015-01-01

    Antibiotics are frequently administered orally to treat bacterial infections not necessarily related to the gastrointestinal system. This has adverse effects on the commensal gut microbial community, as it disrupts the intricate balance between specific bacterial groups within this ecosystem, potentially leading to dysbiosis. We hypothesized that modulation of community composition and function induced by antibiotics affects intestinal integrity depending on the antibiotic administered. To address this a total of 60 Wistar rats (housed in pairs with 6 cages per group) were dosed by oral gavage with either amoxicillin (AMX), cefotaxime (CTX), vancomycin (VAN), metronidazole (MTZ), or water (CON) daily for 10–11 days. Bacterial composition, alpha diversity and caecum short chain fatty acid levels were significantly affected by AMX, CTX and VAN, and varied among antibiotic treatments. A general decrease in diversity and an increase in the relative abundance of Proteobacteria was observed for all three antibiotics. Additionally, the relative abundance of Bifidobacteriaceae was increased in the CTX group and both Lactobacillaceae and Verrucomicrobiaceae were increased in the VAN group compared to the CON group. No changes in microbiota composition or function were observed following MTZ treatment. Intestinal permeability to 4 kDa FITC-dextran decreased after CTX and VAN treatment and increased following MTZ treatment. Plasma haptoglobin levels were increased by both AMX and CTX but no changes in expression of host tight junction genes were found in any treatment group. A strong correlation between the level of caecal succinate, the relative abundance of Clostridiaceae 1 family in the caecum, and the level of acute phase protein haptoglobin in blood plasma was observed. In conclusion, antibiotic-induced changes in microbiota may be linked to alterations in intestinal permeability, although the specific interactions remain to be elucidated as changes in permeability did

  16. Modeling Hysteresis Effect in Three-Phase Relative Permeability

    NASA Astrophysics Data System (ADS)

    Kianinejad, A.; Chen, X.; DiCarlo, D. A.

    2014-12-01

    Simulation and fluid flow prediction of many petroleum enhanced oil recovery methods as well as environmental processes such as carbon dioxide (CO2) geological storage requires accurate modeling and determination of relative permeability under different saturation histories. Based on this critical need, there has been several different three-phase relative permeability models developed to predict the hysteresis effects in relative permeability, most of which requiring many different parameters which introduce extreme complexity to the models for practical purposes. In this work, we experimentally measured three-phase, water/oil/gas, relative permeability in a 1-m long water-wet sand pack, under several different flow histories. We measured the in-situ saturations along the sand pack using a CT scanner. We then determined the relative permeabilities directly from the measured in-situ saturations, using unsteady-state method. Based on our results, good estimation of residual saturations yields in excellent three-phase relative permeability estimations by just using the simple, standard relative permeability models such as, Saturation Weighted Interpolation (SWI), Corey's and Stones. Our results show that, the key parameter to model the hysteresis in three-phase relative permeability (effect of saturation history) is the residual saturations. Once the residual saturations were correctly determined for each specific saturation path, the standard relative permeability models can predict the three-phase relative permeabilities perfectly.

  17. Direct numerical simulation of turbulent channel flow with permeable walls

    NASA Astrophysics Data System (ADS)

    Hahn, Seonghyeon; Je, Jongdoo; Choi, Haecheon

    2002-01-01

    The main objectives of this study are to suggest a proper boundary condition at the interface between a permeable block and turbulent channel flow and to investigate the characteristics of turbulent channel flow with permeable walls. The boundary condition suggested is an extended version of that applied to laminar channel flow by Beavers & Joseph (1967) and describes the behaviour of slip velocities in the streamwise and spanwise directions at the interface between the permeable block and turbulent channel flow. With the proposed boundary condition, direct numerical simulations of turbulent channel flow that is bounded by the permeable wall are performed and significant skin-friction reductions at the permeable wall are obtained with modification of overall flow structures. The viscous sublayer thickness is decreased and the near-wall vortical structures are significantly weakened by the permeable wall. The permeable wall also reduces the turbulence intensities, Reynolds shear stress, and pressure and vorticity fluctuations throughout the channel except very near the wall. The increase of some turbulence quantities there is due to the slip-velocity fluctuations at the wall. The boundary condition proposed for the permeable wall is validated by comparing solutions with those obtained from a separate direct numerical simulation using both the Brinkman equation for the interior of a permeable block and the Navier Stokes equation for the main channel bounded by a permeable block.

  18. Air sparging in low permeability soils

    SciTech Connect

    Marley, M.C.

    1996-08-01

    Sparging technology is rapidly growing as a preferred, low cost remediation technique of choice at sites across the United States. The technology is considered to be commercially available and relatively mature. However, the maturity is based on the number of applications of the technology as opposed to the degree of understanding of the mechanisms governing the sparging process. Few well documented case studies exist on the long term operation of the technology. Sparging has generally been applied using modified monitoring well designs in uniform, coarse grained soils. The applicability of sparging for the remediation of DNAPLs in low permeability media has not been significantly explored. Models for projecting the performance of sparging systems in either soils condition are generally simplistic but can be used to provide general insight into the effects of significant changes in soil and fluid properties. The most promising sparging approaches for the remediation of DNAPLs in low permeability media are variations or enhancements to the core technology. Recirculatory sparging systems, sparging/biosparging trenches or curtains and heating or induced fracturing techniques appear to be the most promising technology variants for this type of soil. 21 refs., 9 figs.

  19. Reservoir permeability from seismic attribute analysis

    SciTech Connect

    Silin, Dmitriy; Goloshubin, G.; Silin, D.; Vingalov, V.; Takkand, G.; Latfullin, M.

    2008-02-15

    In case of porous fluid-saturated medium the Biot's poroelasticity theory predicts a movement of the pore fluid relative to the skeleton on seismic wave propagation through the medium. This phenomenon opens an opportunity for investigation of the flow properties of the hydrocarbon-saturated reservoirs. It is well known that relative fluid movement becomes negligible at seismic frequencies if porous material is homogeneous and well cemented. In this case the theory predicts an underestimated seismic wave velocity dispersion and attenuation. Based on Biot's theory, Helle et al. (2003) have numerically demonstrated the substantial effects on both velocity and attenuation by heterogeneous permeability and saturation in the rocks. Besides fluid flow effect, the effects of scattering (Gurevich, et al., 1997) play very important role in case of finely layered porous rocks and heterogeneous fluid saturation. We have used both fluid flow and scattering effects to derive a frequency-dependent seismic attribute which is proportional to fluid mobility and applied it for analysis of reservoir permeability.

  20. Modeling of microvascular permeability changes after electroporation.

    PubMed

    Corovic, Selma; Markelc, Bostjan; Dolinar, Mitja; Cemazar, Maja; Jarm, Tomaz

    2015-01-01

    Vascular endothelium selectively controls the transport of plasma contents across the blood vessel wall. The principal objective of our preliminary study was to quantify the electroporation-induced increase in permeability of blood vessel wall for macromolecules, which do not normally extravasate from blood into skin interstitium in homeostatic conditions. Our study combines mathematical modeling (by employing pharmacokinetic and finite element modeling approach) with in vivo measurements (by intravital fluorescence microscopy). Extravasation of fluorescently labeled dextran molecules of two different sizes (70 kDa and 2000 kDa) following the application of electroporation pulses was investigated in order to simulate extravasation of therapeutic macromolecules with molecular weights comparable to molecular weight of particles such as antibodies and plasmid DNA. The increase in blood vessel permeability due to electroporation and corresponding transvascular transport was quantified by calculating the apparent diffusion coefficients for skin microvessel wall (D [μm2/s]) for both molecular sizes. The calculated apparent diffusion coefficients were D = 0.0086 μm2/s and D = 0.0045 μm2/s for 70 kDa and 2000 kDa dextran molecules, respectively. The results of our preliminary study have important implications in development of realistic mathematical models for prediction of extravasation and delivery of large therapeutic molecules to target tissues by means of electroporation. PMID:25793292

  1. Modeling of microvascular permeability changes after electroporation.

    PubMed

    Corovic, Selma; Markelc, Bostjan; Dolinar, Mitja; Cemazar, Maja; Jarm, Tomaz

    2015-01-01

    Vascular endothelium selectively controls the transport of plasma contents across the blood vessel wall. The principal objective of our preliminary study was to quantify the electroporation-induced increase in permeability of blood vessel wall for macromolecules, which do not normally extravasate from blood into skin interstitium in homeostatic conditions. Our study combines mathematical modeling (by employing pharmacokinetic and finite element modeling approach) with in vivo measurements (by intravital fluorescence microscopy). Extravasation of fluorescently labeled dextran molecules of two different sizes (70 kDa and 2000 kDa) following the application of electroporation pulses was investigated in order to simulate extravasation of therapeutic macromolecules with molecular weights comparable to molecular weight of particles such as antibodies and plasmid DNA. The increase in blood vessel permeability due to electroporation and corresponding transvascular transport was quantified by calculating the apparent diffusion coefficients for skin microvessel wall (D [μm2/s]) for both molecular sizes. The calculated apparent diffusion coefficients were D = 0.0086 μm2/s and D = 0.0045 μm2/s for 70 kDa and 2000 kDa dextran molecules, respectively. The results of our preliminary study have important implications in development of realistic mathematical models for prediction of extravasation and delivery of large therapeutic molecules to target tissues by means of electroporation.

  2. Efficient high-permeability fracturing offshore

    SciTech Connect

    Phillipi, M.; Farabee, M.

    1996-12-31

    Offshore operators can more efficiently and effectively perform high-permeability and conventional hydraulic fracture treatments by blending treatment slurries under microprocessor control, adding undiluted acid on-the-fly, and altering sand concentrations and other slurry properties instantaneously. A two-skid system has been designed with these considerations in mind. The system, which can be shipped efficiently in ISO containers, has been tested on fluids up to 210-cp viscosity and can step or ramp sand concentrations up to a maximum of 20 lb/gal. All additives, including acid treatments, are added on-the-fly; leftover additives and acids may be stored for future jobs. The system may be applied in most conditions, including offshore wells requiring conventional or high-permeability fracture treatments and certain land-based wells in remote areas where a compact skid is needed. Three significant benefits have resulted from using the compact-skid system: offshore operators have been able to ship the skid system at 20% of shipping costs of non-ISO equipment; on-the-fly mixing has prevented material waste associated with batch-mixing; and volumes pumped on actual jobs have closely matched job designs. Data have been collected from several Gulf of Mexico jobs run with the two-part skid system that has been designed for conducting hydraulic fracture treatments from offshore rigs.

  3. Modeling of Microvascular Permeability Changes after Electroporation

    PubMed Central

    Corovic, Selma; Markelc, Bostjan; Dolinar, Mitja; Cemazar, Maja; Jarm, Tomaz

    2015-01-01

    Vascular endothelium selectively controls the transport of plasma contents across the blood vessel wall. The principal objective of our preliminary study was to quantify the electroporation-induced increase in permeability of blood vessel wall for macromolecules, which do not normally extravasate from blood into skin interstitium in homeostatic conditions. Our study combines mathematical modeling (by employing pharmacokinetic and finite element modeling approach) with in vivo measurements (by intravital fluorescence microscopy). Extravasation of fluorescently labeled dextran molecules of two different sizes (70 kDa and 2000 kDa) following the application of electroporation pulses was investigated in order to simulate extravasation of therapeutic macromolecules with molecular weights comparable to molecular weight of particles such as antibodies and plasmid DNA. The increase in blood vessel permeability due to electroporation and corresponding transvascular transport was quantified by calculating the apparent diffusion coefficients for skin microvessel wall (D [μm2/s]) for both molecular sizes. The calculated apparent diffusion coefficients were D = 0.0086 μm2/s and D = 0.0045 μm2/s for 70 kDa and 2000 kDa dextran molecules, respectively. The results of our preliminary study have important implications in development of realistic mathematical models for prediction of extravasation and delivery of large therapeutic molecules to target tissues by means of electroporation. PMID:25793292

  4. Hantaviruses direct endothelial cell permeability by sensitizing cells to the vascular permeability factor VEGF, while angiopoietin 1 and sphingosine 1-phosphate inhibit hantavirus-directed permeability.

    PubMed

    Gavrilovskaya, Irina N; Gorbunova, Elena E; Mackow, Natalie A; Mackow, Erich R

    2008-06-01

    Hantaviruses infect human endothelial cells and cause two vascular permeability-based diseases: hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. Hantavirus infection alone does not permeabilize endothelial cell monolayers. However, pathogenic hantaviruses inhibit the function of alphav beta3 integrins on endothelial cells, and hemorrhagic disease and vascular permeability deficits are consequences of dysfunctional beta3 integrins that normally regulate permeabilizing vascular endothelial growth factor (VEGF) responses. Here we show that pathogenic Hantaan, Andes, and New York-1 hantaviruses dramatically enhance the permeability of endothelial cells in response to VEGF, while the nonpathogenic hantaviruses Prospect Hill and Tula have no effect on endothelial cell permeability. Pathogenic hantaviruses directed endothelial cell permeability 2 to 3 days postinfection, coincident with pathogenic hantavirus inhibition of alphav beta3 integrin functions, and hantavirus-directed permeability was inhibited by antibodies to VEGF receptor 2 (VEGFR2). These studies demonstrate that pathogenic hantaviruses, similar to alphav beta3 integrin-deficient cells, specifically enhance VEGF-directed permeabilizing responses. Using the hantavirus permeability assay we further demonstrate that the endothelial-cell-specific growth factor angiopoietin 1 (Ang-1) and the platelet-derived lipid mediator sphingosine 1-phosphate (S1P) inhibit hantavirus directed endothelial cell permeability at physiologic concentrations. These results demonstrate the utility of a hantavirus permeability assay and rationalize the testing of Ang-1, S1P, and antibodies to VEGFR2 as potential hantavirus therapeutics. The central importance of beta3 integrins and VEGF responses in vascular leak and hemorrhagic disease further suggest that altering beta3 or VEGF responses may be a common feature of additional viral hemorrhagic diseases. As a result, our findings provide a potential mechanism

  5. Calculation of large scale relative permeabilities from stochastic properties of the permeability field and fluid properties

    SciTech Connect

    Lenormand, R.; Thiele, M.R.

    1997-08-01

    The paper describes the method and presents preliminary results for the calculation of homogenized relative permeabilities using stochastic properties of the permeability field. In heterogeneous media, the spreading of an injected fluid is mainly sue to the permeability heterogeneity and viscosity fingering. At large scale, when the heterogeneous medium is replaced by a homogeneous one, we need to introduce a homogenized (or pseudo) relative permeability to obtain the same spreading. Generally, is derived by using fine-grid numerical simulations (Kyte and Berry). However, this operation is time consuming and cannot be performed for all the meshes of the reservoir. We propose an alternate method which uses the information given by the stochastic properties of the field without any numerical simulation. The method is based on recent developments on homogenized transport equations (the {open_quotes}MHD{close_quotes} equation, Lenormand SPE 30797). The MHD equation accounts for the three basic mechanisms of spreading of the injected fluid: (1) Dispersive spreading due to small scale randomness, characterized by a macrodispersion coefficient D. (2) Convective spreading due to large scale heterogeneities (layers) characterized by a heterogeneity factor H. (3) Viscous fingering characterized by an apparent viscosity ration M. In the paper, we first derive the parameters D and H as functions of variance and correlation length of the permeability field. The results are shown to be in good agreement with fine-grid simulations. The are then derived a function of D, H and M. The main result is that this approach lead to a time dependent . Finally, the calculated are compared to the values derived by history matching using fine-grid numerical simulations.

  6. Effect of Nesting on the Permeability of Multilayer Unidirectional Fabrics

    NASA Astrophysics Data System (ADS)

    Jiang, Jianjun; Su, Yang; Zhou, Linchao; Guo, Qiang; Xu, Chumeng; Deng, Guoli; Chen, Xing; Yao, Xuming; Fang, Liangchao

    2016-10-01

    Nesting of layers is the main source of the variations in permeability values in liquid composite molding (LCM) processes. In this paper, the permeability of unidirectional fabrics was modeled as a function of layer shift and geometrical yarn parameters to study the effect of nesting. Firstly, three different unit cells of two layers were modeled based on the range of layer shift and decomposed into zones of characteristic yarn arrangement, respectively. The overall permeability of each unit cell was then modeled as a mixture of local permeabilities of different zones with the electrical resistance analogy. Secondly, every two adjacent layers were regarded as porous media with different permeabilities. The permeability of multilayer unidirectional fabrics was then modeled with electrical resistance analogy. As the unpredictability of layer shifting in actual process, the statistical characteristics were analyzed theoretically and validated with experimental measurements. Excellent agreement was found between predictions and experiment data.

  7. Intestinal permeability in patients with acute myeloid leukemia.

    PubMed

    Sundström, G M; Wahlin, A; Nordin-Andersson, I; Suhr, O B

    1998-10-01

    Intestinal permeability was studied in patients with acute myeloid leukemia (AML) before, during and after chemotherapy. Intestinal permeability was determined by the lactulose (La)/mannitol (Ma) absorption test in 16 adult patients with de novo AML. The hydrogen breath test was used to disclose bacterial fermentation of the test substances in the small intestine. The permeability was found significantly increased (p<0.02) in the patients before induction chemotherapy treatment. During induction treatment and throughout the cytopenic period the intestinal permeability was constantly and significantly increased, compared with controls. In patients with abnormally increased permeability, no increase in hydrogen breath test result was noted. From our results it can be concluded that increased intestinal permeability is present in AML patients before commencing chemotherapy. Factors other than chemotherapy would seem to be more important regarding the occurrence of intestinal disturbances in these patients.

  8. Intestinal permeability study of minoxidil: assessment of minoxidil as a high permeability reference drug for biopharmaceutics classification.

    PubMed

    Ozawa, Makoto; Tsume, Yasuhiro; Zur, Moran; Dahan, Arik; Amidon, Gordon L

    2015-01-01

    The purpose of this study was to evaluate minoxidil as a high permeability reference drug for Biopharmaceutics Classification System (BCS). The permeability of minoxidil was determined in in situ intestinal perfusion studies in rodents and permeability studies across Caco-2 cell monolayers. The permeability of minoxidil was compared with that of metoprolol, an FDA reference drug for BCS classification. In rat perfusion studies, the permeability of minoxidil was somewhat higher than that of metoprolol in the jejunum, while minoxidil showed lower permeability than metoprolol in the ileum. The permeability of minoxidil was independent of intestinal segment, while the permeability of metoprolol was region-dependent. Similarly, in mouse perfusion study, the jejunal permeability of minoxidil was 2.5-fold higher than that of metoprolol. Minoxidil and metoprolol showed similar permeability in Caco-2 study at apical pH of 6.5 and basolateral pH of 7.4. The permeability of minoxidil was independent of pH, while metoprolol showed pH-dependent transport in Caco-2 study. Minoxidil exhibited similar permeability in the absorptive direction (AP-BL) in comparison with secretory direction (BL-AP), while metoprolol had higher efflux ratio (ER > 2) at apical pH of 6.5 and basolateral pH of 7.4. No concentration-dependent transport was observed for either minoxidil or metoprolol transport in Caco-2 study. Verapamil did not alter the transport of either compounds across Caco-2 cell monolayers. The permeability of minoxidil was independent of both pH and intestinal segment in intestinal perfusion studies and Caco-2 studies. Caco-2 studies also showed no involvement of carrier mediated transport in the absorption process of minoxidil. These results suggest that minoxidil may be an acceptable reference drug for BCS high permeability classification. However, minoxidil exhibited higher jejunal permeability than metoprolol and thus to use minoxidil as a reference drug would raise the

  9. Characteristics of permeability in carbonate areas of Korea

    NASA Astrophysics Data System (ADS)

    Park, Y.; Lee, J.; Lim, H.; Keehm, Y.

    2010-12-01

    Permeability (hydraulic conductivity) in carbonate areas is affected by various factors such as fracture, pore and degree of weathering and diagenesis. Also, caves developed in carbonate area are main factors. This study was performed to understand factors controlling the permeability in carbonate areas in Korea. In order to conduct this study, the permeability and well logging data (n=30) were collected from many literatures and rock samples were collected around wells. Vertical profile of the carbonate areas can be classified into soil, weathered carbonate and fresh carbonate zone. They show a different range at each region. Most of the rock samples were hardly weathered. The permeability showed wide ranges (0.009 to 1.1 m/day). The average value of the permeability was 0.159 m/day. However, 80% (n=24) of total data had the permeability valves lower than 0.1 m/day. The permeability values were distinguished according to degree of development of fractures. The permeability showed low values (approximately <0.04 m/day) in hardly fractured carbonate area, intermediate values (approximately 0.04 to 0.5 m/day) in fractured carbonate area and high values (approximately >0.5 m/day) in highly fractured carbonate. These results mean that fractures are dominant factors controlling the permeability in carbonate areas of Korea than others. This work was supported by Energy Resource R&D program (2009T100200058) under the Ministry of Knowledge Economy, Republic of Korea.

  10. Influence of decenylsuccinic Acid on water permeability of plant cells.

    PubMed

    Lee, O Y; Stadelmann, E J; Weiser, C J

    1972-11-01

    Decenylsuccinic acid altered permeability to water of epidermal cells of bulb scales of Allium cepa and of the leaf midrib of Rhoeo discolor. Water permeability, as determined by deplasmolysis time measurements, was related to the dose of undissociated decenylsuccinic acid (mm undissociated decenylsuccinic acid x minute). No relationship was found between permeability and total dose of decenylsuccinic acid, or dose of dissociated decenylsuccinic acid, suggesting that the undissociated molecule was the active factor in permeability changes and injury.At doses which did not damage cells (0.0008 to 0.6 [mm of the undissociated molecule x minute]) decenylsuccinic acid decreased water permeability. At higher doses (e.g., 4 to 8 [mm x minute]) injury to cells was common and decenylsuccinic acid increased permeability. Doses above the 10 to 20 (mm x minute) range were generally lethal. The plasmolysis form of uninjured cells was altered and protoplasmic swelling occasionally was observed. The dose-dependent reversal of water permeability changes (decreased to increased permeability) may reflect decenylsuccinic acid-induced changes in membrane structure. Reported effects of decenylsuccinic acid on temperature dependence of permeability and frost resistance were not verified. PMID:16658227

  11. Permeability of continental crust influenced by internal and external forcing

    USGS Publications Warehouse

    Rojstaczer, S.A.; Ingebritsen, S.E.; Hayba, D.O.

    2008-01-01

    The permeability of continental crust is so highly variable that it is often considered to defy systematic characterization. However, despite this variability, some order has been gleaned from globally compiled data. What accounts for the apparent coherence of mean permeability in the continental crust (and permeability-depth relations) on a very large scale? Here we argue that large-scale crustal permeability adjusts to accommodate rates of internal and external forcing. In the deeper crust, internal forcing - fluxes induced by metamorphism, magmatism, and mantle degassing - is dominant, whereas in the shallow crust, external forcing - the vigor of the hydrologic cycle - is a primary control. Crustal petrologists have long recognized the likelihood of a causal relation between fluid flux and permeability in the deep, ductile crust, where fluid pressures are typically near-lithostatic. It is less obvious that such a relation should pertain in the relatively cool, brittle upper crust, where near-hydrostatic fluid pressures are the norm. We use first-order calculations and numerical modeling to explore the hypothesis that upper-crustal permeability is influenced by the magnitude of external fluid sources, much as lower-crustal permeability is influenced by the magnitude of internal fluid sources. We compare model-generated permeability structures with various observations of crustal permeability. ?? 2008 The Authors Journal compilation ?? 2008 Blackwell Publishing Ltd.

  12. Osmotic Flow through Fully Permeable Nanochannels

    NASA Astrophysics Data System (ADS)

    Lee, C.; Cottin-Bizonne, C.; Biance, A.-L.; Joseph, P.; Bocquet, L.; Ybert, C.

    2014-06-01

    Osmosis across membranes is intrinsically associated with the concept of semipermeability. Here, however, we demonstrate that osmotic flow can be generated by solute gradients across nonselective, fully permeable nanochannels. Using a fluorescence imaging technique, we are able to measure the water flow rate inside single nanochannels to an unprecedented sensitivity of femtoliters per minute flow rates. Our results indicate the onset of a convective liquid motion under salinity gradients, from the higher to lower electrolyte concentration, which is attributed to diffusio-osmotic transport. To our knowledge, this is the first experimental evidence and quantitative investigation of this subtle interfacially driven transport, which need to be accounted for in nanoscale dynamics. Finally, diffusio-osmotic transport under a neutral polymer gradient is also demonstrated. The experiments highlight the entropic depletion of polymers that occurs at the nanochannel surface, resulting in convective flow in the opposite direction to that seen for electrolytes.

  13. Ground rubber: Reactive permeable barrier sorption media

    SciTech Connect

    Kershaw, D.S.; Pamukcu, S.

    1997-12-31

    The objective of this research was to examine the feasibility of using ground tire rubber as a sorbent media in reactive permeable barrier systems. Previous research by the current authors has demonstrated that tire rubber can sorb significant quantities of benzene, toluene, ethylbenzene and O-xylene from aqueous solutions. The current research was run to examine the usage rate of ground rubber in a packed bed reactor under specific contact times. In addition, desorption and repetitive sorption tests were run to determine the reversibility of the sorption process for ground tire rubber. These tests were run to determine the regeneration capacity of ground tire rubber. Results of the study show that the usage rates are greater than 50% with an empty bed contact times of 37 minutes, and minimal amounts of energy are needed to regenerate the tire rubber after use.

  14. Composite Crew Module (CCM) Permeability Characterization

    NASA Technical Reports Server (NTRS)

    Kirsch, Michael T.

    2013-01-01

    In January 2007, the NASA Administrator chartered the NASA Engineering and Safety Center (NESC) to form an Agency team to design and build a composite crew module in 18 months in order to gain hands-on experience in anticipation that future exploration systems may be made of composite materials. One of the conclusions from this Composite Crew Module Primary Structure assessment was that there was a lack of understanding regarding the ability for composite pressure shells to contain consumable gases, which posed a technical risk relative to the use of a metallic design. After the completion of the Composite Crew Module test program, the test article was used in a new program to assess the overall leakage/permeability and identify specific features associated with high leak rates. This document contains the outcome of the leakage assessment.

  15. Fluid permeability measurement system and method

    DOEpatents

    Hallman, Jr., Russell Louis; Renner, Michael John

    2008-02-05

    A system for measuring the permeance of a material. The permeability of the material may also be derived. The system provides a liquid or high concentration fluid bath on one side of a material test sample, and a gas flow across the opposing side of the material test sample. The mass flow rate of permeated fluid as a fraction of the combined mass flow rate of gas and permeated fluid is used to calculate the permeance of the material. The material test sample may be a sheet, a tube, or a solid shape. Operational test conditions may be varied, including concentration of the fluid, temperature of the fluid, strain profile of the material test sample, and differential pressure across the material test sample.

  16. Biomimetic Hybrid Nanocontainers with Selective Permeability.

    PubMed

    Messager, Lea; Burns, Jonathan R; Kim, Jungyeon; Cecchin, Denis; Hindley, James; Pyne, Alice L B; Gaitzsch, Jens; Battaglia, Giuseppe; Howorka, Stefan

    2016-09-01

    Chemistry plays a crucial role in creating synthetic analogues of biomacromolecular structures. Of particular scientific and technological interest are biomimetic vesicles that are inspired by natural membrane compartments and organelles but avoid their drawbacks, such as membrane instability and limited control over cargo transport across the boundaries. In this study, completely synthetic vesicles were developed from stable polymeric walls and easy-to-engineer membrane DNA nanopores. The hybrid nanocontainers feature selective permeability and permit the transport of organic molecules of 1.5 nm size. Larger enzymes (ca. 5 nm) can be encapsulated and retained within the vesicles yet remain catalytically active. The hybrid structures constitute a new type of enzymatic nanoreactor. The high tunability of the polymeric vesicles and DNA pores will be key in tailoring the nanocontainers for applications in drug delivery, bioimaging, biocatalysis, and cell mimicry. PMID:27560310

  17. Gas permeable electrode for electrochemical system

    DOEpatents

    Ludwig, F.A.; Townsend, C.W.

    1989-09-12

    An electrode apparatus is described which is adapted for use in electrochemical systems having an anode compartment and a cathode compartment in which gas and ions are produced and consumed in the compartments during generation of electrical current. The electrode apparatus includes a membrane for separating the anode compartment from the cathode compartment wherein the membrane is permeable to both ions and gas. The cathode and anode for the assembly are provided on opposite sides of the membrane. During use of the membrane-electrode apparatus in electrochemical cells, the gas and ions generated at the cathode or anode migrate through the membrane to provide efficient transfer of gas and ions between the anode and cathode compartments. 3 figs.

  18. Osmotic flow through fully permeable nanochannels.

    PubMed

    Lee, C; Cottin-Bizonne, C; Biance, A-L; Joseph, P; Bocquet, L; Ybert, C

    2014-06-20

    Osmosis across membranes is intrinsically associated with the concept of semipermeability. Here, however, we demonstrate that osmotic flow can be generated by solute gradients across nonselective, fully permeable nanochannels. Using a fluorescence imaging technique, we are able to measure the water flow rate inside single nanochannels to an unprecedented sensitivity of femtoliters per minute flow rates. Our results indicate the onset of a convective liquid motion under salinity gradients, from the higher to lower electrolyte concentration, which is attributed to diffusio-osmotic transport. To our knowledge, this is the first experimental evidence and quantitative investigation of this subtle interfacially driven transport, which need to be accounted for in nanoscale dynamics. Finally, diffusio-osmotic transport under a neutral polymer gradient is also demonstrated. The experiments highlight the entropic depletion of polymers that occurs at the nanochannel surface, resulting in convective flow in the opposite direction to that seen for electrolytes. PMID:24996091

  19. Composite binders for concrete with reduced permeability

    NASA Astrophysics Data System (ADS)

    Fediuk, R.; Yushin, A.

    2016-02-01

    Composite binder consisting of cement (55%), acid fly ash (40%) and limestone (5%) has been designed. It is obtained by co-milling to a specific surface of 550 kg/m2, it has an activity of 77.3 MPa and can produce a more dense cement stone structure. Integrated study revealed that the concrete on the composite binder basis provides an effective diffusion coefficient D. So we can conclude that the concrete layer protects buildings from toxic effects of expanded polystyrene. Low water absorption of the material (2.5% by weight) is due to the structure of its cement stone pore space. Besides lime powder prevents the penetration of moisture, reduces water saturation of the coverage that has a positive effect on useful life period. It also explains rather low water vapor permeability of the material - 0.021 mg/(m- hour-Pa).

  20. Glassy Dynamics, Cell Mechanics and Endothelial Permeability

    PubMed Central

    Hardin, Corey; Rajendran, Kavitha; Manomohan, Greeshma; Tambe, Dhananjay T.; Butler, James P.; Fredberg, Jeffrey J.; Martinelli, Roberta; Carman, Christopher V.; Krishnan, Ramaswamy

    2013-01-01

    A key feature of all inflammatory processes is disruption of the vascular endothelial barrier. Such disruption is initiated in part through active contraction of the cytoskeleton of the endothelial cell (EC). Because contractile forces are propagated from cell to cell across a great many cell-cell junctions, this contractile process is strongly cooperative and highly nonlocal. We show here that the characteristic length scale of propagation is modulated by agonists and antagonists that impact permeability of the endothelial barrier. In the presence of agonists including thrombin, histamine, and H202, force correlation length increases, whereas in the presence of antagonists including sphingosine-1-phosphate, hepatocyte growth factor, and the rho kinase inhibitor, Y27632, force correlation length decreases. Intercellular force chains and force clusters are also evident, both of which are reminiscent of soft glassy materials approaching a glass transition. PMID:23638866

  1. Back diffusion from thin low permeability zones.

    PubMed

    Yang, Minjune; Annable, Michael D; Jawitz, James W

    2015-01-01

    Aquitards can serve as long-term contaminant sources to aquifers when contaminant mass diffuses from the aquitard following aquifer source mass depletion. This study describes analytical and experimental approaches to understand reactive and nonreactive solute transport in a thin aquitard bounded by an adjacent aquifer. A series of well-controlled laboratory experiments were conducted in a two-dimensional flow chamber to quantify solute diffusion from a high-permeability sand into and subsequently out of kaolinite clay layers of vertical thickness 15 mm, 20 mm, and 60 mm. One-dimensional analytical solutions were developed for diffusion in a finite aquitard with mass exchange with an adjacent aquifer using the method of images. The analytical solutions showed very good agreement with measured breakthrough curves and aquitard concentration distributions measured in situ by light reflection visualization. Solutes with low retardation accumulated more stored mass with greater penetration distance in the aquitard compared to high-retardation solutes. However, because the duration of aquitard mass release was much longer, high-retardation solutes have a greater long-term back diffusion risk. The error associated with applying a semi-infinite domain analytical solution to a finite diffusion domain increases as a function of the system relative diffusion length scale, suggesting that the solutions using image sources should be applied in cases with rapid solute diffusion and/or thin clay layers. The solutions presented here can be extended to multilayer aquifer/low-permeability systems to assess the significance of back diffusion from thin layers.

  2. Colloid transport in dual-permeability media.

    PubMed

    Leij, Feike J; Bradford, Scott A

    2013-07-01

    It has been widely reported that colloids can travel faster and over longer distances in natural structured porous media than in uniform structureless media used in laboratory studies. The presence of preferential pathways for colloids in the subsurface environment is of concern because of the increased risks for disease caused by microorganisms and colloid-associated contaminants. This study presents a model for colloid transport in dual-permeability media that includes reversible and irreversible retention of colloids and first-order exchange between the aqueous phases of the two regions. The model may also be used to describe transport of other reactive solutes in dual-permeability media. Analytical solutions for colloid concentrations in aqueous and solid phases were obtained using Laplace transformation and matrix decomposition. The solutions proved convenient to assess the effect of model parameters on the colloid distribution. The analytical model was used to describe effluent concentrations for a bromide tracer and 3.2- or 1-μm-colloids that were observed after transport through a composite 10-cm long porous medium made up of a cylindrical lens or core of sand and a surrounding matrix with sand of a different grain size. The tracer data were described very well and realistic estimates were obtained for the pore-water velocity in the two flow domains. An accurate description was also achieved for most colloid breakthrough curves. Dispersivity and retention parameters were typically greater for the larger 3.2-μm-colloids while both reversible and irreversible retention rates tended to be higher for the finer sands than the coarser sand. The relatively small sample size and the complex flow pattern in the composite medium made it difficult to reach definitive conclusions regarding transport parameters for colloid transport.

  3. Back diffusion from thin low permeability zones.

    PubMed

    Yang, Minjune; Annable, Michael D; Jawitz, James W

    2015-01-01

    Aquitards can serve as long-term contaminant sources to aquifers when contaminant mass diffuses from the aquitard following aquifer source mass depletion. This study describes analytical and experimental approaches to understand reactive and nonreactive solute transport in a thin aquitard bounded by an adjacent aquifer. A series of well-controlled laboratory experiments were conducted in a two-dimensional flow chamber to quantify solute diffusion from a high-permeability sand into and subsequently out of kaolinite clay layers of vertical thickness 15 mm, 20 mm, and 60 mm. One-dimensional analytical solutions were developed for diffusion in a finite aquitard with mass exchange with an adjacent aquifer using the method of images. The analytical solutions showed very good agreement with measured breakthrough curves and aquitard concentration distributions measured in situ by light reflection visualization. Solutes with low retardation accumulated more stored mass with greater penetration distance in the aquitard compared to high-retardation solutes. However, because the duration of aquitard mass release was much longer, high-retardation solutes have a greater long-term back diffusion risk. The error associated with applying a semi-infinite domain analytical solution to a finite diffusion domain increases as a function of the system relative diffusion length scale, suggesting that the solutions using image sources should be applied in cases with rapid solute diffusion and/or thin clay layers. The solutions presented here can be extended to multilayer aquifer/low-permeability systems to assess the significance of back diffusion from thin layers. PMID:25478850

  4. Colloid transport in dual-permeability media

    NASA Astrophysics Data System (ADS)

    Leij, Feike J.; Bradford, Scott A.

    2013-07-01

    It has been widely reported that colloids can travel faster and over longer distances in natural structured porous media than in uniform structureless media used in laboratory studies. The presence of preferential pathways for colloids in the subsurface environment is of concern because of the increased risks for disease caused by microorganisms and colloid-associated contaminants. This study presents a model for colloid transport in dual-permeability media that includes reversible and irreversible retention of colloids and first-order exchange between the aqueous phases of the two regions. The model may also be used to describe transport of other reactive solutes in dual-permeability media. Analytical solutions for colloid concentrations in aqueous and solid phases were obtained using Laplace transformation and matrix decomposition. The solutions proved convenient to assess the effect of model parameters on the colloid distribution. The analytical model was used to describe effluent concentrations for a bromide tracer and 3.2- or 1-μm-colloids that were observed after transport through a composite 10-cm long porous medium made up of a cylindrical lens or core of sand and a surrounding matrix with sand of a different grain size. The tracer data were described very well and realistic estimates were obtained for the pore-water velocity in the two flow domains. An accurate description was also achieved for most colloid breakthrough curves. Dispersivity and retention parameters were typically greater for the larger 3.2-μm-colloids while both reversible and irreversible retention rates tended to be higher for the finer sands than the coarser sand. The relatively small sample size and the complex flow pattern in the composite medium made it difficult to reach definitive conclusions regarding transport parameters for colloid transport.

  5. Hormonal regulation of hepatocyte tight junctional permeability

    SciTech Connect

    Lowe, P.J.; Miyai, K.; Steinbach, J.H.; Hardison, W.G.M. Univ. of California, San Diego )

    1988-10-01

    The authors have investigated the effects of hormones on the permeability of the hepatocyte tight junction to two probes, ({sup 14}C)sucrose and horseradish peroxidase, using one-pass perfused rat livers. Using a single injection of horseradish peroxidase the authors have demonstrated that this probe can enter bile by two pathways that are kinetically distinct, a fast pathway, which corresponds to the passage of the probe through the hepatocyte tight junctions, and a slow pathway, which corresponds to the transcytotic entry into bile. The passage of horseradish peroxidase through the hepatocyte tight junctions was confirmed by electron microscopic histochemistry. Vasopressin, epinephrine, and angiotensin II, hormones that act in the hepatocyte through the intracellular mediators calcium, the inositol polyphosphates, and diacylglycerol, increased the bile-to-perfusion fluid ratio of ({sup 14}C)sucrose and the rapid entry of horseradish peroxidase into bile, indicating that the permeability of the tight junctions to these probes was increased. The effect of these hormones was dose dependent and in the cases of angiotensin II and epinephrine was inhibited by the specific inhibitors (Sar{sup 1},Thr{sup 8})angiotensin II and prazosin, respectively. Dibutyryl adenosine 3{prime},5{prime}-cyclic monophosphate did not affect the ({sup 14}C)sucrose bile-to-perfusion fluid ratio or the fast entry of horseradish peroxidase into bile. These results suggest that the hepatocyte tight junction can no longer be considered a static system of pores separating blood from bile. It is rather a dynamic barrier potentially capable of influencing the composition of the bile.

  6. Turbulent Hyporheic Exchange in Permeable Sediments

    NASA Astrophysics Data System (ADS)

    Roche, K. R.; Aubeneau, A. F.; Li, A.; Packman, A. I.

    2015-12-01

    Solute delivery from the water column into a streambed strongly influences metabolism in rivers. Current hydrological models simplify surface-subsurface (hyporheic) exchange by treating each domain separately, constraining turbulent flows to the water column. Studies have shown, however, that turbulence penetrates into permeable sediments. Evidence is lacking for how this highly coupled flow regime influences hyporheic exchange. We characterized the dynamics of turbulent exchange between surface and porewaters in a 2.5 m recirculating flume. The channel was packed with 3.8 cm PVC spheres to form a coarse gravel bed, with a total depth of 21 cm. We implanted microsensors onto an array of spheres to measure in situsalt concentrations within the streambed. Water was recirculated in the channel, and concentrated salt solution was continuously injected upstream of the sensor array. We observed solute exchange increased with free-stream Reynolds number and decreased with depth in the sediment bed. Mass of injected solute remaining in the bed decreased rapidly in all cases, with only 10-30% of mass recovered 50 cm downstream of the injection point at Re = 25,000. We observed high-frequency (1-10 Hz) concentration fluctuations at bed depths of at least 4.75 cm, and sporadic low-frequency fluctuations at depths of 12.5 cm. Spectral analysis revealed increased filtering of high frequencies with depth. We used particle-tracking simulations to fit depth-dependent turbulent diffusion profiles to experimental results. These results demonstrate that free-stream turbulence impacts hyporheic mixing deep into permeable streambeds, and mixing is strongly influenced by the coupled surface-subsurface flow field.

  7. Hydraulic Permeability of Resorcinol-Formaldehyde Resin

    SciTech Connect

    Taylor, Paul Allen

    2010-01-01

    An ion exchange process using spherical resorcinol-formaldehyde (RF) resin is the baseline process for removing cesium from the dissolved salt solution in the high-level waste tanks at the Hanford Site, using large scale columns as part of the Waste Treatment Plant (WTP). The RF resin is also being evaluated for use in the proposed small column ion exchange (SCIX) system, which is an alternative treatment option at Hanford and at the Savannah River Site (SRS). A recirculating test loop with a small ion exchange column was used to measure the effect of oxygen uptake and radiation exposure on the permeability of a packed bed of the RF resin. The lab-scale column was designed to be prototypic of the proposed Hanford columns at the WTP. Although the test equipment was designed to model the Hanford ion exchange columns, the data on changes in the hydraulic permeability of the resin will also be valuable for determining potential pressure drops through the proposed SCIX system. The superficial fluid velocity in the lab-scale test (3.4-5.7 cm/s) was much higher than is planned for the full-scale Hanford columns to generate the maximum pressure drop expected in those columns (9.7 psig). The frictional drag from this high velocity produced forces on the resin in the lab-scale tests that matched the design basis of the full-scale Hanford column. Any changes in the resin caused by the radiation exposure and oxygen uptake were monitored by measuring the pressure drop through the lab-scale column and the physical properties of the resin. Three hydraulic test runs were completed, the first using fresh RF resin at 25 C, the second using irradiated resin at 25 C, and the third using irradiated resin at 45 C. A Hanford AP-101 simulant solution was recirculated through a test column containing 500 mL of Na-form RF resin. Known amounts of oxygen were introduced into the primary recirculation loop by saturating measured volumes of the simulant solution with oxygen and reintroducing

  8. Permeability of alkaline magmas: a study from Campi Flegrei, Italy

    NASA Astrophysics Data System (ADS)

    Polacci, M.; Bouvet de Maissoneuve, C.; Giordano, D.; Piochi, M.; Degruyter, W.; Bachmann, O.; Mancini, L.

    2012-04-01

    Knowledge of permeability is of paramount importance for understanding the evolution of magma degassing during pre-, syn- and post-eruptive volcanic processes. Most permeability estimates existing to date refer to magmas of calc-alkaline compositions. We report here the preliminary results of permeability measurements performed on alkali-trachyte products erupted from the Campanian Ignimbrite (CI) and Monte Nuovo (MTN), two explosive eruptions from Campi Flegrei (CF), an active, hazardous caldera west of Naples, Southern Italy. Darcian (viscous) permeability spans a wide range between 10^-11 and 10^-14 m^2. We observe that the most permeable samples are the scoria clasts from the upper units of MTN; pumice samples from the Breccia Museo facies of CI are instead the least permeable. Non-Darcian (inertial) permeability follows the same trend as Darcian permeability. The first implication of this study is that porosity in alkaline as well as calc-alkaline magmas does not exert a first order control on permeability (e.g. the MTN samples are the most permeable but not the most porous). Second, sample geometry exhibits permeability anisotropy (higher permeability in the direction of vesicle elongation), suggesting stronger degassing in the vertical direction in the conduit. In addition, inertial effects are higher across the sample. As inertial effects are potentially generated by tortuosity (or tortuous vesicle paths), tortuosity is likely higher horizontally than vertically in the conduit. Finally, the measured CF permeability values overlap with those of rhyolitic pumice clasts from the Kos Plateau Tuff (Bouvet de Maisonneuve et al., 2009), together with CI one of the major Quaternary explosive eruptions of the Mediterranean region. This indicates that gas flow is strongly controlled by the geometry of the porous media, which is generated by the bubble dynamics during magma ascent. Therefore, permeability will depend on composition through the rheological properties

  9. Hepatic Injury in Nonalcoholic Steatohepatitis Contributes to Altered Intestinal Permeability

    PubMed Central

    Luther, Jay; Garber, John J.; Khalili, Hamed; Dave, Maneesh; Bale, Shyam Sundhar; Jindal, Rohit; Motola, Daniel L.; Luther, Sanjana; Bohr, Stefan; Jeoung, Soung Won; Deshpande, Vikram; Singh, Gurminder; Turner, Jerrold R.; Yarmush, Martin L.; Chung, Raymond T.; Patel, Suraj J.

    2015-01-01

    BACKGROUND & AIMS Emerging data suggest that changes in intestinal permeability and increased gut microbial translocation contribute to the inflammatory pathway involved in nonalcoholic steatohepatitis (NASH) development. Numerous studies have investigated the association between increased intestinal permeability and NASH. Our meta-analysis of this association investigates the underlying mechanism. METHODS A meta-analysis was performed to compare the rates of increased intestinal permeability in patients with NASH and healthy controls. To further address the underlying mechanism of action, we studied changes in intestinal permeability in a diet-induced (methionine-and-choline-deficient; MCD) murine model of NASH. In vitro studies were also performed to investigate the effect of MCD culture medium at the cellular level on hepatocytes, Kupffer cells, and intestinal epithelial cells. RESULTS Nonalcoholic fatty liver disease (NAFLD) patients, and in particular those with NASH, are more likely to have increased intestinal permeability compared with healthy controls. We correlate this clinical observation with in vivo data showing mice fed an MCD diet develop intestinal permeability changes after an initial phase of liver injury and tumor necrosis factor-α (TNFα) induction. In vitro studies reveal that MCD medium induces hepatic injury and TNFα production yet has no direct effect on intestinal epithelial cells. Although these data suggest a role for hepatic TNFα in altering intestinal permeability, we found that mice genetically resistant to TNFα-myosin light chain kinase (MLCK)–induced intestinal permeability changes fed an MCD diet still develop increased permeability and liver injury. CONCLUSIONS Our clinical and experimental results strengthen the association between intestinal permeability increases and NASH and also suggest that an early phase of hepatic injury and inflammation contributes to altered intestinal permeability in a fashion independent of TNF

  10. Evaluation of the permeability of agricultural films to various fumigants.

    PubMed

    Qian, Yaorong; Kamel, Alaa; Stafford, Charles; Nguyen, Thuy; Chism, William J; Dawson, Jeffrey; Smith, Charles W

    2011-11-15

    A variety of agricultural films are commercially available for managing emissions and enhancing pest control during soil fumigation. These films are manufactured using different materials and processes which can ultimately result in different permeability to fumigants. A systematic laboratory study of the permeability of the agricultural films to nine fumigants was conducted to evaluate the performance of commonly used film products, including polyethylene, metalized, and high-barrier films. The permeability, as expressed by mass transfer coefficient (cm/h), of 27 different films from 13 manufacturers ranged from below 1 × 10(-4) cm/h to above 10 cm/h at 25 °C under ambient relative humidity test conditions. The wide range in permeability of commercially available films demonstrates the need to use films which are appropriate for the fumigation application. The effects of environmental factors, such as temperature and humidity, on the film permeability were also investigated. It was found that high relative humidity could drastically increase the permeability of the high-barrier films. The permeability of some high-barrier films was increased by 2-3 orders of magnitude when the films were tested at high relative humidity. Increasing the temperature from 25 to 40 °C increased the permeability for some high-barrier films up to 10 times more than the permeability at 25 °C, although the effect was minimal for several of these films. Analysis of the distribution of the permeability of the films under ambient humidity conditions to nine fumigants indicated that the 27 films largely followed the material type, although the permeability varied considerably among the films of similar material.

  11. Porosity and permeability evolution of clay faults: in situ experiments

    NASA Astrophysics Data System (ADS)

    Henry, P.; Guglielmi, Y.; Seguy, S.; Lefevre, M.; Ghani, I.; Gent, G.; Castilla, R.; Gout, C.; Dick, P.; Nussbaum, C.; Durand, J.

    2015-12-01

    Fault models associating low permeability cores with high permeability damage zones are widely accepted, however, constitutive laws relating permeability with fault structure, stress, and strain remain poorly constrained. We here present preliminary results of hydromechanical experiments performed at the 10 m scale in fault zones in Toarcian and Aalenian black shale formations. Intact formations have a very low permeability (10-19 to 10-22 m2). One case (in IRSN's Tournemire Underground Research Laboratory) displays a porosity increase in and around the fault core and abundant veins and calcite cemented small faults in the damage zone. The other case (Mont Terri Swisstopo Underground Research Laboratory) displays a porosity decrease in the fault core zone and few veins. However, under the present stress state, the static permeability of the fractured zones at both locations is higher than that of the intact formation by up to 3 orders of magnitude. During borehole pressurization tests three regimes of permeability variations are observed. (1) Fracture permeability first increases progressively as a function of fluid pressure (2) When a threshold is reached, permeability further increases by 100 or more, but strain as well as permeability variations remain in most part reversible. (3) When a steady pressure is maintained in the injection borehole (from 20 minutes to several days) flow rate tends to decrease with time. These results show that high transient permeability may locally occur in a fault zone under conditions when most of the deformation is reversible, opening the possibility of transient fluid migration decoupled from slip along faults that are not favorably oriented. However, during one test, more than 1 mm of irreversible slip occurred along one of the main interfaces, associated with a sudden increase in flow rate (from 11 to more than 40 l/min). This suggests that when slip occurs, it could result in permeability variations that may remain difficult

  12. Further investigations of why gels reduce water permeability more than oil permeability

    SciTech Connect

    Liang, J.T.; Seright, R.S.

    1997-11-01

    In this paper, the authors investigate why some gels can reduce the permeability to water much more than to oil. This property is critical to the success of chemical-based water-shutoff treatments in production wells if hydrocarbon-productive zones cannot be protected during placement. The authors first briefly review previous findings and the validity of several possible explanations for this disproportionate permeability reduction. Next, they describe experiments that test the validity of a promising mechanism--the segregated pathway theory. This theory speculates that on a microscopic scale, aqueous gelants follow water pathways more than oil pathways. Experimental results in cores support this mechanism for oil-based gels, but not for water-based gels. They also explore another interesting mechanism that involves a balance between capillary and elastic forces. Results from experiments support this mechanism for flow in tubes and micromodels, but not in porous rock. Other mechanisms are also discussed.

  13. PREFERENTIAL RADON TRANSPORT THROUGH HIGHLY PERMEABLE CHANNELS IN SOILS

    EPA Science Inventory

    The paper discusses preferential radon transport through highly permeable channels in soils. Indoor radon levels (that can pose a serious health risk) can be dramatically increased by air that is drawn into buildings through pipe penetrations that connect to permeable channels in...

  14. Permeable Pavement Research at the Edison Environmental Center

    EPA Science Inventory

    There are few detailed studies of full-scale, replicated, actively-used permeable pavement systems. Practitioners need additional studies of permeable pavement systems in its intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage conditio...

  15. Permeable Textual Discussion in Tracked Language Arts Classrooms

    ERIC Educational Resources Information Center

    Gritter, Kristine

    2012-01-01

    Permeable textual discussion occurs when the unofficial texts and discursive practices and personal histories that are already recognized and valued in students' cultures are scaffolds to academically sanctioned literacies. Ideally, permeable textual discussions are safe havens where students' identities (racial, gender, world views) are…

  16. Hydrogen-permeable composite metal membrane and uses thereof

    DOEpatents

    Edlund, David J.; Friesen, Dwayne T.

    1993-06-08

    Various hydrogen production and hydrogen sulfide decomposition processes are disclosed that utilize composite metal membranes that contain an intermetallic diffusion barrier separating a hydrogen-permeable base metal and a hydrogen-permeable coating metal. The barrier is a thermally stable inorganic proton conductor.

  17. Nitrogen Transformations in Three Types of Permeable Pavement

    EPA Science Inventory

    In 2009, USEPA constructed a 0.4-ha (1-ac) parking lot at the Edison Environmental Center in Edison, NJ, that incorporated three different permeable pavement types - permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA). The driving lanes...

  18. Selective permeability of PVA membranes. I - Radiation-crosslinked membranes

    NASA Technical Reports Server (NTRS)

    Katz, M. G.; Wydeven, T., Jr.

    1981-01-01

    The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

  19. Selective Permeability of PVA Membranes. I: Radiation-Crosslinked Membranes

    NASA Technical Reports Server (NTRS)

    Katz, Moshe G.; Wydeven, Theodore, Jr.

    1981-01-01

    The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

  20. Determination of Coal Permeability Using Pressure Transient Methods

    SciTech Connect

    McLendon, T.R.; Siriwardane, H.; Haljasmaa, I.V.; Bromhal, G.S.; Soong, Y.; Irdi, G.A.

    2007-05-01

    Coalbed methane is a significant natural resource in the Appalachian region. It is believed that coalbed methane production can be enhanced by injection of carbon dioxide into coalbeds. However, the influence of carbon dioxide injection on coal permeability is not yet well understood. Competitive sorption of carbon dioxide and methane gases onto coal is a known process. Laboratory experiments and limited field experience indicate that coal will swell during sorption of a gas and shrink during desorption of a gas. The swelling and shrinkage may change the permeability of the coal. In this study, the permeability of coal was determined by using carbon dioxide as the flowing fluid. Coal samples with different dimensions were prepared for laboratory permeability tests. Carbon dioxide was injected into the coal and the permeability was determined by using pressure transient methods. The confining pressure was variedto cover a wide range of depths. The permeability was also determined as a function of exposure time of carbon dioxide while the confining stress was kept constant. CT scans were taken before and after the introduction of carbon dioxide. Results show that the porosity and permeability of the coal matrix was very low. The paper presents experimental data and theoretical aspects of the flow of carbon dioxide through a coal sample during pressure transient tests. The suitability of the pressure transient methods for determining permeability of coal during carbon dioxide injection is discussed in the paper.

  1. Mapping permeability over the surface of the Earth

    USGS Publications Warehouse

    Gleeson, T.; Smith, L.; Moosdorf, N.; Hartmann, J.; Durr, H.H.; Manning, A.H.; Van Beek, L. P. H.; Jellinek, A. Mark

    2011-01-01

    Permeability, the ease of fluid flow through porous rocks and soils, is a fundamental but often poorly quantified component in the analysis of regional-scale water fluxes. Permeability is difficult to quantify because it varies over more than 13 orders of magnitude and is heterogeneous and dependent on flow direction. Indeed, at the regional scale, maps of permeability only exist for soil to depths of 1-2 m. Here we use an extensive compilation of results from hydrogeologic models to show that regional-scale (>5 km) permeability of consolidated and unconsolidated geologic units below soil horizons (hydrolithologies) can be characterized in a statistically meaningful way. The representative permeabilities of these hydrolithologies are used to map the distribution of near-surface (on the order of 100 m depth) permeability globally and over North America. The distribution of each hydrolithology is generally scale independent. The near-surface mean permeability is of the order of ???5 ?? 10-14 m2. The results provide the first global picture of near-surface permeability and will be of particular value for evaluating global water resources and modeling the influence of climate-surface-subsurface interactions on global climate change. Copyright ?? 2011 by the American Geophysical Union.

  2. Unsaturated and Saturated Permeabilities of Fiber Reinforcement: Critics and Suggestions

    NASA Astrophysics Data System (ADS)

    Park, Chung Hae; Krawczak, Patricia

    2015-04-01

    In general, permeability measurement results show a strong scattering according to the measurement method, the type of test fluid and the fluid injection condition, even though permeability is regarded as a unique property of porous medium. In particular, the discrepancy between the unsaturated and saturated permeabilities for the same fabric has been widely reported. In the literature, relative permeability has been adopted to model the unsaturated flow. This approach has some limits in the modeling of double-scale porosity medium. We address this issue of permeability measurement by rigorously examining the mass conservation condition. Finally, we identify that the pressure gradient is non-linear with positive curvature in the unsaturated flow and a misinterpretation of pressure gradient is the main reason for the difference between the saturated and unsaturated permeabilities of the same fiber reinforcement. We propose to use a fixed value of permeability and to modify the mass conservation equation if there are air voids which are entrapped inside the fiber tow. Finally, we also suggest some guidelines and future perspectives to obtain more consistent permeability measurement results.

  3. Effective parameterizations of three nonwetting phase relative permeability models

    NASA Astrophysics Data System (ADS)

    Yang, Zhenlei; Mohanty, Binayak P.

    2015-08-01

    Describing convective nonwetting phase flow in unsaturated porous media requires knowledge of the nonwetting phase relative permeability. This study was conducted to formulate and derive a generalized expression for the nonwetting phase relative permeability via combining with the Kosugi water retention function. This generalized formulation is then used to flexibly investigate the Burdine, Mualem, and Alexander and Skaggs models' prediction accuracy for relative nonwetting phase permeability. The model and data comparison results show that these three permeability models, if used in their original form, but applied to the nonwetting phase, could not predict the experimental data well. The optimum pore tortuosity and connectivity value is thus obtained for the improved prediction of relative nonwetting phase permeability. As a result, the effective parameterization of (α,β,η) parameters in the modified Burdine, modified Mualem, and modified Alexander and Skaggs permeability models were found to be (2.5, 2, 1), (2, 1, 2), and (2.5, 1, 1), respectively. These three suggested models display the highest accuracy among the nine relative permeability models investigated in this study. However, the corresponding discontinuous nonwetting phase and the liquid film flow should be accounted for in future for the improved prediction of nonwetting phase relative permeability at very high and very low water saturation range, respectively.

  4. Mapping permeability over the surface of the Earth

    USGS Publications Warehouse

    Gleeson, Tom; Smith, Leslie; Moosdorf, Nils; Hartmann, Jens; Durr, Hans H.; Manning, Andrew H.; van Beek, Ludovicus P. H.; Jellinek, A. Mark

    2011-01-01

    Permeability, the ease of fluid flow through porous rocks and soils, is a fundamental but often poorly quantified component in the analysis of regional-scale water fluxes. Permeability is difficult to quantify because it varies over more than 13 orders of magnitude and is heterogeneous and dependent on flow direction. Indeed, at the regional scale, maps of permeability only exist for soil to depths of 1-2 m. Here we use an extensive compilation of results from hydrogeologic models to show that regional-scale (>5 km) permeability of consolidated and unconsolidated geologic units below soil horizons (hydrolithologies) can be characterized in a statistically meaningful way. The representative permeabilities of these hydrolithologies are used to map the distribution of near-surface (on the order of 100 m depth) permeability globally and over North America. The distribution of each hydrolithology is generally scale independent. The near-surface mean permeability is of the order of -5 x 10-14 m2. The results provide the first global picture of near-surface permeability and will be of particular value for evaluating global water resources and modeling the influence of climate-surface-subsurface interactions on global climate change.

  5. Permeability of small nonelectrolytes through lipid bilayer membranes

    SciTech Connect

    Walter, A.; Gutknecht, J.

    1986-01-01

    Diffusion of small nonelectrolytes through planar lipid bilayer membranes (egg phosphatidylcholine-decane) was examined by correlating the permeability coefficients of 22 solutes with their partition coefficients between water and four organic solvents. High correlations were observed with hexadecane and olive oil (r = 0.95 and 0.93), but not octanol and ether (r = 0.75 and 0.74). Permeabilities of the seven smallest molecules (mol wt less than 50) (water, hydrofluoric acid, hydrochloric acid, ammonia, methylamine, formic acid and formamide) were 2- to 15-fold higher than the values predicted by the permeabilities of the larger molecules (50 less than mol wt less than 300). The extra permeabilities of the seven smallest molecules were not correlated with partition coefficients but were inversely correlated with molecular volumes. The larger solute permeabilities also decreased with increasing molecular volume, but the relationship was neither steep nor significant. The permeability pattern cannot be explained by the molecular volume dependence of partitioning into the bilayer or by the existence of transient aqueous pores. The molecular volume dependence of solute permeability suggests that the membrane barrier behaves more like a polymer than a liquid hydrocarbon. All the data are consistent with the solubility-diffusion model, which can explain both the hydrophobicity dependence and the molecular volume dependence of nonelectrolyte permeability.

  6. Determination of hydrogen permeability in uncoated and coated superalloys

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, S.; Vesely, E. J., Jr.; Hill, V. L.

    1981-01-01

    Hydrogen permeability, diffusivity, and solubility data were obtained for eight wrought and cast high temperature alloys over the range 650 to 815 C. Data were obtained for both uncoated alloys and wrought alloys coated with four commercially available coatings. Activation energies for permeability, diffusivity and solubility were calculated.

  7. Permeability of hydrogen isotopes through nickel-based alloys

    SciTech Connect

    Edge, E.M.; Mitchell, D.J.

    1983-04-01

    Permeabilities and diffusivities of deuterium in several nickel-based alloys were measured in this investigation. Measurements were made by the gas-phase breakthrough technique in the temperature range 200 to 450/sup 0/C with applied pressures ranging from 1 to 100 kPa. The results were extrapolated to predict the permeabilities (K) of the alloys at room temperature. The alloy with the smallest deuterium permeability is Carpenter 49, for which K = 4.3 x 10/sup -18/ mol s/sup -1/ m/sup -1/ Pa/sup -//sup 1/2/ at 22/sup 0/C. The permeability of deuterium in Kovar or Ceramvar is about 80% greater than that for Carpenter 49. Premeabilities of Inconel 625, Inconel 718, Inconel 750 and Monel K-500 are all equal to about 5 x 10/sup -17/ mol m/sup -1/ s/sup -1/ Pa/sup -//sup 1/2/ at 22/sup 0/C. The validity (from a statistical standpoint) of the extrapolation of the permeabilities to room temperature is considered in detail. Published permeabilities of stainless steels and nickel-iron alloys are also reviewed. The greatest differences in permeabilities among the nickel-based alloys appear to be associated with the tendency for some alloys to form protective oxide layers. Permeabilities of deuterium through laminates containing copper are smaller than for any of the iron-nickel alloys.

  8. Nanochannel flow past permeable walls via molecular dynamics

    NASA Astrophysics Data System (ADS)

    Xie, Jian-Fei; Cao, Bing-Yang

    2016-07-01

    The nanochannel flow past permeable walls with nanopores is investigated by molecular dynamics (MD) simulations, including the density distribution, velocity field, molecular penetration mechanism and surface friction coefficient. A low density distribution has been found at the gas-wall interface demonstrating the low pressure region. In addition, there exists a jump of the gas density on the permeable surface, which indicates the discontinuity of the density distribution across the permeable surface. On the other hand, the nanoscale vortices are observed in nanopores of the permeable wall, and the reduced mass flux of the flow in nanopores results in a shifted hydrodynamic boundary above the permeable surface. Particularly the slip length of the gas flow on the permeable surface is pronounced a non-linear function of the molecular mean free path, which produces a large value of the tangential momentum accommodation coefficient (TMAC) and a big portion of the diffusive refection. Moreover, the gas-gas interaction and multi-collision among gas molecules may take place in nanopores, which contribute to large values of TMAC. Consequently the boundary friction coefficient on the permeable surface is increased because of the energy dissipation consumed by the nanoscale vortices in nanopores. The molecular boundary condition provides us with a new picture of the nanochannel flow past the permeable wall with nanopores.

  9. The structure of turbulence overlying impermeable and permeable rough walls

    NASA Astrophysics Data System (ADS)

    Kim, T.; Blois, G.; Best, J.; Christensen, K. T.

    2014-11-01

    Turbulent flow overlying complex topographies, both impermeable and permeable, occur across a broad range of scales in both natural and engineering environments. Permeability of the wall introduces a higher degree of both structural and conceptual complexity, with previous studies suggesting that interactions between the turbulent free flow and pore flow occur along the permeable interface and play a defining role in momentum exchange across the interface. Here we employ a Refractive-Index-Matching (RIM) technique in order to access the flow across the permeable interface with the particle image velocimetry (PIV) method, resulting in unimpeded optical access to the fluid flow at and within a permeable bed. Cubic-packed hemispheres are studied in both impermeable and permeable configurations, with models cast by an acrylic resin whose refractive index matched that of the working fluid (aqueous sodium iodide). The statistical and structural features of the flow in the near-wall region of the impermeable case and the interfacial region of the permeable case are compared to understand the role of permeability in driving momentum exchange processes as a function of Reynolds number. Comparisons to recent numerical simulations are also made.

  10. Modeling the Hydrologic Processes of a Permeable Pavement System

    EPA Science Inventory

    A permeable pavement system can capture stormwater to reduce runoff volume and flow rate, improve onsite groundwater recharge, and enhance pollutant controls within the site. A new unit process model for evaluating the hydrologic performance of a permeable pavement system has be...

  11. The Permeability of Territorial Space: Some Evidence from Military Warfare.

    ERIC Educational Resources Information Center

    Khoury, Robert M.

    1984-01-01

    Investigated military invasions (N=58) of the territorial boundaries of nation-states, and attempted to document empirically the territorial space permeability function. Results showed that the function relating intrusion to discomfort was found to be conspicuously similar to the personal space permeability function described by Hayduk (1981).…

  12. Extreme Rainfall Impacts in Fractured Permeable Catchments

    NASA Astrophysics Data System (ADS)

    Ireson, A. M.; Butler, A. P.

    2009-12-01

    Serious groundwater flooding events have occurred on Chalk catchments in both the UK and north west Europe in the last decade, causing substantial amounts of disruption and economic damage. These fractured, permeable catchments are characterized by low surface runoff, high baseflow indices and strongly attenuated streamflow hydrographs. They have a general resilience to drought and pluvial/fluvial flooding. The small pore size of the Chalk matrix (~ 1 µm) exerts a high suction, such that dynamic storage is primarily due to the fractures, and amounts to ~ 1% of the total volume. As a result, under sustained rainfall the water table can rise up to exceptional levels leading to surface water emergence from springs and valleys. Floodwater may slowly drain with the topography, or, in localized depressions, it may simply pond until the groundwater levels decline. In winter 2000/1, a sequence of individually unexceptional rainfall events over several months led to large scale flooding in the Pang catchment, Berkshire, UK. By contrast, an extreme rainfall event on 20th July 2007 in the same catchment caused a very rapid response at the water table, but due to the antecedent conditions did not lead to flooding. The objective of this study is to quantify how the water table in a fractured permeable catchment responds to different types of rainfall, and the implications of this for groundwater flooding. We make use of measurements from the Pang catchment, including: rainfall (tipping bucket gauges); actual evaporation (eddy flux correlation); soil water content (profile probes and neutron probes); near surface matric potential (tensiometers and equitensiometers); deep (>10m) matric potential (deep jacking tensiometers); and water table elevation (piezometers). Conventional treatment of recharge in Chalk aquifers considers a fixed bypass component of rainfall, normally 15%, to account for the role of the fractures. However, interpretation of the field data suggest three modes

  13. Predicting skin permeability from complex chemical mixtures

    SciTech Connect

    Riviere, Jim E. . E-mail: Jim_Riviere@ncsu.edu; Brooks, James D.

    2005-10-15

    Occupational and environmental exposure to topical chemicals is usually in the form of complex chemical mixtures, yet risk assessment is based on experimentally derived data from individual chemical exposures from a single, usually aqueous vehicle, or from computed physiochemical properties. We present an approach using hybrid quantitative structure permeation relationships (QSPeR) models where absorption through porcine skin flow-through diffusion cells is well predicted using a QSPeR model describing the individual penetrants, coupled with a mixture factor (MF) that accounts for physicochemical properties of the vehicle/mixture components. The baseline equation is log k {sub p} = c + mMF + a{sigma}{alpha} {sub 2} {sup H} + b{sigma}{beta} {sub 2} {sup H} + s{pi} {sub 2} {sup H} + rR {sub 2} + vV {sub x} where {sigma}{alpha} {sub 2} {sup H} is the hydrogen-bond donor acidity, {sigma}{beta} {sub 2} {sup H} is the hydrogen-bond acceptor basicity, {pi} {sub 2} {sup H} is the dipolarity/polarizability, R {sub 2} represents the excess molar refractivity, and V {sub x} is the McGowan volume of the penetrants of interest; c, m, a, b, s, r, and v are strength coefficients coupling these descriptors to skin permeability (k {sub p}) of 12 penetrants (atrazine, chlorpyrifos, ethylparathion, fenthion, methylparathion, nonylphenol, {rho}-nitrophenol, pentachlorophenol, phenol, propazine, simazine, and triazine) in 24 mixtures. Mixtures consisted of full factorial combinations of vehicles (water, ethanol, propylene glycol) and additives (sodium lauryl sulfate, methyl nicotinate). An additional set of 4 penetrants (DEET, SDS, permethrin, ricinoleic acid) in different mixtures were included to assess applicability of this approach. This resulted in a dataset of 16 compounds administered in 344 treatment combinations. Across all exposures with no MF, R{sup 2} for absorption was 0.62. With the MF, correlations increased up to 0.78. Parameters correlated to the MF include refractive

  14. Predicting the extent of metabolism using in vitro permeability rate measurements and in silico permeability rate predictions

    PubMed Central

    Hosey, Chelsea M; Benet, Leslie Z

    2015-01-01

    The Biopharmaceutics Drug Disposition Classification System (BDDCS) can be utilized to predict drug disposition, including interactions with other drugs and transporter or metabolizing enzyme effects based on the extent of metabolism and solubility of a drug. However, defining the extent of metabolism relies upon clinical data. Drugs exhibiting high passive intestinal permeability rates are extensively metabolized. Therefore, we aimed to determine if in vitro measures of permeability rate or in silico permeability rate predictions could predict the extent of metabolism, to determine a reference compound representing the permeability rate above which compounds would be expected to be extensively metabolized, and to predict the major route of elimination of compounds in a two-tier approach utilizing permeability rate and a previously published model predicting the major route of elimination of parent drug. Twenty-two in vitro permeability rate measurement data sets in Caco-2 and MDCK cell lines and PAMPA were collected from the literature, while in silico permeability rate predictions were calculated using ADMET Predictor™ or VolSurf+. The potential for permeability rate to differentiate between extensively and poorly metabolized compounds was analyzed with receiver operating characteristic curves. Compounds that yielded the highest sensitivity-specificity average were selected as permeability rate reference standards. The major route of elimination of poorly permeable drugs was predicted by our previously published model and the accuracies and predictive values were calculated. The areas under the receiver operating curves were >0.90 for in vitro measures of permeability rate and >0.80 for the VolSurf+ model of permeability rate, indicating they were able to predict the extent of metabolism of compounds. Labetalol and zidovudine predicted greater than 80% of extensively metabolized drugs correctly and greater than 80% of poorly metabolized drugs correctly in Caco

  15. The influence of age and weaning on permeability of the gastrointestinal tract in Holstein bull calves.

    PubMed

    Wood, K M; Palmer, S I; Steele, M A; Metcalf, J A; Penner, G B

    2015-10-01

    Fourteen Holstein bull calves were used in a randomized complete block design to investigate the effect of calf age and weaning on permeability of the gastrointestinal tract (GIT). Calves were randomly assigned to 1 of 2 treatments: (1) a weaning protocol that was initiated on d 35; WN; n=7), or (2) a control treatment where calves were not weaned (CON; n=7). Calves were bottle-fed milk replacer (150 g/L), in 3 equal portions/d targeting 15% of their body weight (BW) in liquid milk intake [approximately 21.1g/kg of BW/d, dry matter (DM) basis]. On d 35, the amount of milk replacer offered to WN calves was reduced to 7.5% of BW for 7 d before calves were weaned on d 42. On d 14, 28, and 42, calves were orally dosed with 500 mL of Cr-EDTA (179 mM Cr-EDTA solution) and housed in a metabolism crate to enable total urine collection and determination of total urinary Cr recovery as an indicator of total-tract permeability. On d 44, calves were killed and tissues from the rumen, omasum, duodenum, jejunum, ileum, cecum, and proximal and distal colon were collected, rinsed, and transported in buffer solution (pH 7.4 at 38.5°C). Tissues were incubated in Ussing chambers under short-circuit conditions with buffer solutions designed to mimic the mucosal and serosal energy source that would be available in vivo (glucose for tissues from the small intestine and short-chain fatty acids for tissues that would be exposed to fermentation; rumen, omasum, and large intestinal tissues). The serosal to mucosal flux of (14)C-mannitol and (3)H-inulin was measured for each region. Although we detected treatment × period interactions for BW and starter intake, dietary treatments did not differ within a week. Overall, the time that ruminal pH was <5.5 was less before weaning than after weaning. We observed a differential response for the appearance of Cr in urine for WN and CON calves, where the appearance of Cr (mg/48 h) in urine decreased for both treatments from d 14 to 28, but

  16. Intrinsic delay of permeable base transistor

    SciTech Connect

    Chen, Wenchao; Guo, Jing; So, Franky

    2014-07-28

    Permeable base transistors (PBTs) fabricated by vacuum deposition or solution process have the advantages of easy fabrication and low power operation and are a promising device structure for flexible electronics. Intrinsic delay of PBT, which characterizes the speed of the transistor, is investigated by solving the three-dimensional Poisson equation and drift-diffusion equation self-consistently using finite element method. Decreasing the emitter thickness lowers the intrinsic delay by improving on-current, and a thinner base is also preferred for low intrinsic delay because of fewer carriers in the base region at off-state. The intrinsic delay exponentially decreases as the emitter contact Schottky barrier height decreases, and it linearly depends on the carrier mobility. With an optimized emitter contact barrier height and device geometry, a sub-nano-second intrinsic delay can be achieved with a carrier mobility of ∼10 cm{sup 2}/V/s obtainable in solution processed indium gallium zinc oxide, which indicates the potential of solution processed PBTs for GHz operations.

  17. Drainage hydraulics of permeable friction courses

    NASA Astrophysics Data System (ADS)

    Charbeneau, Randall J.; Barrett, Michael E.

    2008-04-01

    This paper describes solutions to the hydraulic equations that govern flow in permeable friction courses (PFC). PFC is a layer of porous asphalt approximately 50 mm thick that is placed as an overlay on top of an existing conventional concrete or asphalt road surface to help control splash and hydroplaning, reduce noise, and enhance quality of storm water runoff. The primary objective of this manuscript is to present an analytical system of equations that can be used in design and analysis of PFC systems. The primary assumptions used in this analysis are that the flow can be modeled as one-dimensional, steady state Darcy-type flow and that slopes are sufficiently small so that the Dupuit-Forchheimer assumptions apply. Solutions are derived for cases where storm water drainage is confined to the PFC bed and for conditions where the PFC drainage capacity is exceeded and ponded sheet flow occurs across the pavement surface. The mathematical solutions provide the drainage characteristics (depth and residence time) as a function of rainfall intensity, PFC hydraulic conductivity, pavement slope, and maximum drainage path length.

  18. Self-organized permeability in carbonate aquifers.

    PubMed

    Worthington, S R H; Ford, D C

    2009-01-01

    Advances over the past 40 years have resulted in a clear understanding of how dissolution processes in carbonate rocks enhance aquifer permeability. Laboratory experiments on dissolution rates of calcite and dolomite have established that there is a precipitous drop in dissolution rates as chemical equilibrium is approached. These results have been incorporated into numerical models, simulating the effects of dissolution over time and showing that it occurs along the entire length of pathways through carbonate aquifers. The pathways become enlarged and integrated over time, forming self-organized networks of channels that typically have apertures in the millimeter to centimeter range. The networks discharge at point-located springs. Recharge type is an important factor in determining channel size and distribution, resulting in a range of aquifer types, and this is well demonstrated by examples from England. Most carbonate aquifers have a large number of small channels, but in some cases large channels (i.e., enterable caves) can also develop. Rapid velocities found in ground water tracer tests, the high incidence of large-magnitude springs, and frequent microbial contamination of wells all support the model of self-organized channel development. A large majority of carbonate aquifers have such channel networks, where ground water velocities often exceed 100 m/d.

  19. Second law violations, continuum mechanics, and permeability

    NASA Astrophysics Data System (ADS)

    Ostoja-Starzewski, Martin

    2016-03-01

    The violations of the second law are relevant as the length and/or time scales become very small. The second law then needs to be replaced by the fluctuation theorem and mathematically, the irreversible entropy is a submartingale. First, we discuss the consequences of these results for the axioms of continuum mechanics, arguing in favor of a framework relying on stochastic functionals of energy and entropy. We next determine a Lyapunov function for diffusion-type problems governed by stochastic rather than deterministic functionals of internal energy and entropy, where the random field coefficients of diffusion are not required to satisfy the positive definiteness everywhere. Next, a formulation of micropolar fluid mechanics is developed, accounting for the lack of symmetry of stress tensor on molecular scales. This framework is then applied to employed to show that spontaneous random fluctuations of the microrotation field will arise in Couette—and Poiseuille-type flows in the absence of random (turbulence-like) fluctuations of the classical velocity field. Finally, while the permeability is classically modeled by the Darcy law or its modifications, besides considering the violations of the second law, one also needs to account for the spatial randomness of the channel network, implying a modification of the hierarchy of scale-dependent bounds on the macroscopic property of the network.

  20. Permeability of WIPP Salt During Damage Evolution and Healing

    SciTech Connect

    BODNER,SOL R.; CHAN,KWAI S.; MUNSON,DARRELL E.

    1999-12-03

    The presence of damage in the form of microcracks can increase the permeability of salt. In this paper, an analytical formulation of the permeability of damaged rock salt is presented for both initially intact and porous conditions. The analysis shows that permeability is related to the connected (i.e., gas accessible) volumetric strain and porosity according to two different power-laws, which may be summed to give the overall behavior of a porous salt with damage. This relationship was incorporated into a constitutive model, known as the Multimechanism Deformation Coupled Fracture (MDCF) model, which has been formulated to describe the inelastic flow behavior of rock salt due to coupled creep, damage, and healing. The extended model was used to calculate the permeability of rock salt from the Waste Isolation Pilot Plant (WIPP) site under conditions where damage evolved with stress over a time period. Permeability changes resulting from both damage development under deviatoric stresses and damage healing under hydrostatic pressures were considered. The calculated results were compared against experimental data from the literature, which indicated that permeability in damaged intact WIPP salt depends on the magnitude of the gas accessible volumetric strain and not on the total volumetric strain. Consequently, the permeability of WIPP salt is significantly affected by the kinetics of crack closure, but shows little dependence on the kinetics of crack removal by sintering.

  1. Stress dependence of permeability of intact and fractured shale cores.

    NASA Astrophysics Data System (ADS)

    van Noort, Reinier; Yarushina, Viktoriya

    2016-04-01

    Whether a shale acts as a caprock, source rock, or reservoir, understanding fluid flow through shale is of major importance for understanding fluid flow in geological systems. Because of the low permeability of shale, flow is thought to be largely confined to fractures and similar features. In fracking operations, fractures are induced specifically to allow for hydrocarbon exploration. We have constructed an experimental setup to measure core permeabilities, using constant flow or a transient pulse. In this setup, we have measured the permeability of intact and fractured shale core samples, using either water or supercritical CO2 as the transporting fluid. Our measurements show decreasing permeability with increasing confining pressure, mainly due to time-dependent creep. Furthermore, our measurements show that for a simple splitting fracture, time-dependent creep will also eliminate any significant effect of this fracture on permeability. This effect of confinement on fracture permeability can have important implications regarding the effects of fracturing on shale permeability, and hence for operations depending on that.

  2. [Research on permeability of landfill's body in primary compression].

    PubMed

    Liu, Hui; Huang, Tao; Zhang, Chi

    2009-12-01

    Refuse degradation and landfill leachate treatment are the main research directions of landfill technology at present, but permeability characteristics of landfill body are paid little attention on. According to this actuality, the study selected four kinds of landfill's bodies under different pressures as study objects and tested the permeability characteristics in the stage of main compression settlement. Through the laboratory physical simulation experiments, the results show that the data of determination and analysis on landfill's bodies under four difference pressures conform to Darcy's law. Because the change of COD is in the phase of acid producing, its impact on permeability can not be considered. Based on these conditions, the calculation results of permeability coefficient indicate that during the course of the main compression settlement, the change law of landfill permeability coefficient index is approximately agreed with nature exponential law, expect for the condition of landfill body without pressure. Meanwhile, the landfill permeability coefficient values under four difference pressures are in the range of 10(-4.5)-10(-5.3) m x s(-1), which are consistent with the typical representative values of garbage permeability coefficient.

  3. Relative air permeability as function of saturation in soil venting

    SciTech Connect

    Stylianou, C.; DeVantier, B.A.

    1995-04-01

    Traditionally, soil remediation involved soil flushing, or excavation followed by landfilling or treatment. In recent years, recognizing the major environmental problem of soil contamination by VOCs, soil vapor extraction (SVE, also known as soil venting) has been applied as a form of in situ remediation. A key parameter in modeling soil-venting systems is relative air permeability, determined as a function of liquid saturation. The focus of the present study was to characterize the relationship of the relative air permeability as a function of air saturation in soil-venting systems. A new laboratory apparatus was used to simulate the soil venting and measure the air permeability of soil samples. Sand samples wetted with mixtures of water and gasoline at different ratios were used. It was revealed that the prediction of relative air permeability for moist noncohesive soil can be made in terms of intrinsic permeability and air-filled porosity alone, and not the type of liquid present in the pores. Comparisons of measured data with existing relations for relative air permeability as a function of total liquid saturation were made to determine the most accurate and practical forms for engineering applications. For the sand sample used, the evaluation revealed that compared to the existing relations, a derived second-order polynomial expression provides a good estimate of relative air permeability and does not require estimation of soil-water-retention curve parameters.

  4. Characterization and estimation of permeability correlation structure from performance data

    SciTech Connect

    Ershaghi, I.; Al-Qahtani, M.

    1997-08-01

    In this study, the influence of permeability structure and correlation length on the system effective permeability and recovery factors of 2-D cross-sectional reservoir models, under waterflood, is investigated. Reservoirs with identical statistical representation of permeability attributes are shown to exhibit different system effective permeability and production characteristics which can be expressed by a mean and variance. The mean and variance are shown to be significantly influenced by the correlation length. Detailed quantification of the influence of horizontal and vertical correlation lengths for different permeability distributions is presented. The effect of capillary pressure, P{sub c1} on the production characteristics and saturation profiles at different correlation lengths is also investigated. It is observed that neglecting P{sub c} causes considerable error at large horizontal and short vertical correlation lengths. The effect of using constant as opposed to variable relative permeability attributes is also investigated at different correlation lengths. Next we studied the influence of correlation anisotropy in 2-D reservoir models. For a reservoir under five-spot waterflood pattern, it is shown that the ratios of breakthrough times and recovery factors of the wells in each direction of correlation are greatly influenced by the degree of anisotropy. In fully developed fields, performance data can aid in the recognition of reservoir anisotropy. Finally, a procedure for estimating the spatial correlation length from performance data is presented. Both the production performance data and the system`s effective permeability are required in estimating the correlation length.

  5. Effect of Polycaprolactone Scaffold Permeability on Bone Regeneration In Vivo

    PubMed Central

    Mitsak, Anna G.; Kemppainen, Jessica M.; Harris, Matthew T.

    2011-01-01

    Successful bone tissue engineering depends on the scaffold's ability to allow nutrient diffusion to and waste removal from the regeneration site, as well as provide an appropriate mechanical environment. Since bone is highly vascularized, scaffolds that provide greater mass transport may support increased bone regeneration. Permeability encompasses the salient features of three-dimensional porous scaffold architecture effects on scaffold mass transport. We hypothesized that higher permeability scaffolds will enhance bone regeneration for a given cell seeding density. We manufactured poly-ɛ-caprolactone scaffolds, designed to have the same internal pore design and either a low permeability (0.688×10−7m4/N-s) or a high permeability (3.991×10−7m4/N-s), respectively. Scaffolds were seeded with bone morphogenic protein-7-transduced human gingival fibroblasts and implanted subcutaneously in immune-compromised mice for 4 and 8 weeks. Micro-CT evaluation showed better bone penetration into high permeability scaffolds, with blood vessel infiltration visible at 4 weeks. Compression testing showed that scaffold design had more influence on elastic modulus than time point did and that bone tissue infiltration increased the mechanical properties of the high permeability scaffolds at 8 weeks. These results suggest that for polycaprolactone, a more permeable scaffold with regular architecture is best for in vivo bone regeneration. This finding is an important step toward the end goal of optimizing a scaffold for bone tissue engineering. PMID:21395465

  6. IMPACT OF CAPILLARY AND BOND NUMBERS ON RELATIVE PERMEABILITY

    SciTech Connect

    Kishore K. Mohanty

    2002-09-30

    Recovery and recovery rate of oil, gas and condensates depend crucially on their relative permeability. Relative permeability in turn depends on the pore structure, wettability and flooding conditions, which can be represented by a set of dimensionless groups including capillary and bond numbers. The effect of flooding conditions on drainage relative permeabilities is not well understood and is the overall goal of this project. This project has three specific objectives: to improve the centrifuge relative permeability method, to measure capillary and bond number effects experimentally, and to develop a pore network model for multiphase flows. A centrifuge has been built that can accommodate high pressure core holders and x-ray saturation monitoring. The centrifuge core holders can operate at a pore pressure of 6.9 MPa (1000 psi) and an overburden pressure of 17 MPa (2500 psi). The effect of capillary number on residual saturation and relative permeability in drainage flow has been measured. A pore network model has been developed to study the effect of capillary numbers and viscosity ratio on drainage relative permeability. Capillary and Reynolds number dependence of gas-condensate flow has been studied during well testing. A method has been developed to estimate relative permeability parameters from gas-condensate well test data.

  7. Update to permeable pavement research at the Edison Environmental Center - slides

    EPA Science Inventory

    Abstract: The EPA’s Urban Watershed Management Branch (UWMB) has been monitoring the permeable pavement demonstration site at the Edison Environmental Center, NJ since 2010. This site has three different types of permeable pavement including: interlocking concrete permeable...

  8. Update to Permeable Pavement Research at the Edison Environmental Center - abstract

    EPA Science Inventory

    Abstract The EPA’s Urban Watershed Management Branch (UWMB) has been monitoring the permeable pavement demonstration site at the Edison Environmental Center, NJ since 2010. This site has three different types of permeable pavement including: interlocking concrete permeable ...

  9. Update to Permeable Pavement Research at the Edison Environmental Center - abstract

    EPA Science Inventory

    Abstract The EPA’s Urban Watershed Management Branch (UWMB) has been monitoring the permeable pavement demonstration site at the Edison Environmental Center, NJ since 2010. This site has three different types of permeable pavement including: interlocking concrete permeable pavers...

  10. Update to permeable pavement research at the Edison Environmental Center - slides

    EPA Science Inventory

    Abstract: The EPA’s Urban Watershed Management Branch (UWMB) has been monitoring the permeable pavement demonstration site at the Edison Environmental Center, NJ since 2010. This site has three different types of permeable pavement including: interlocking concrete permeable paver...

  11. Fractal Theory for Permeability Prediction, Venezuelan and USA Wells

    NASA Astrophysics Data System (ADS)

    Aldana, Milagrosa; Altamiranda, Dignorah; Cabrera, Ana

    2014-05-01

    Inferring petrophysical parameters such as permeability, porosity, water saturation, capillary pressure, etc, from the analysis of well logs or other available core data has always been of critical importance in the oil industry. Permeability in particular, which is considered to be a complex parameter, has been inferred using both empirical and theoretical techniques. The main goal of this work is to predict permeability values on different wells using Fractal Theory, based on a method proposed by Pape et al. (1999). This approach uses the relationship between permeability and the geometric form of the pore space of the rock. This method is based on the modified equation of Kozeny-Carman and a fractal pattern, which allows determining permeability as a function of the cementation exponent, porosity and the fractal dimension. Data from wells located in Venezuela and the United States of America are analyzed. Employing data of porosity and permeability obtained from core samples, and applying the Fractal Theory method, we calculated the prediction equations for each well. At the beginning, this was achieved by training with 50% of the data available for each well. Afterwards, these equations were tested inferring over 100% of the data to analyze possible trends in their distribution. This procedure gave excellent results in all the wells in spite of their geographic distance, generating permeability models with the potential to accurately predict permeability logs in the remaining parts of the well for which there are no core samples, using even porority logs. Additionally, empirical models were used to determine permeability and the results were compared with those obtained by applying the fractal method. The results indicated that, although there are empirical equations that give a proper adjustment, the prediction results obtained using fractal theory give a better fit to the core reference data.

  12. Evaluation of air permeability in layered unsaturated materials.

    PubMed

    Switzer, Christine; Kosson, David S

    2007-03-20

    Field estimation of air permeability is important in the design and operation of soil-vapor extraction systems. Previous models have examined airflow in homogenous soils, incorporating leakage through a low-permeability cap either as a correction to the airflow equation or as a boundary condition. The dual leakage model solution developed here improves upon the previous efforts by adding a leaky lower boundary condition, allowing for the examination of airflow in heterogeneous layered soils. The dual leakage model is applied to the evaluation of pump tests at a pilot soil-vapor extraction system at the Savannah River Site in South Carolina. A thick, low-permeability, stiff clay layer divides the stratigraphy at the site into two units for evaluation. A modified version of the previous model, using the water table as the impermeable lower boundary, is used to evaluate the permeability of the low-permeability stiff clay layer (3.2 x 10(-10) cm(2)) and permeable sand (7.2 x 10(-7) cm(2)) beneath it. The stiff clay permeability estimate is used in the evaluation of the shallow unit. Permeability estimates of the shallow sand (3.8 x 10(-7) cm(2)) and kaolin cap (1.5 x 10(-9)cm(2)) were obtained with the dual leakage model. The shallow unit was evaluated using the previous model for comparison. The effects of anisotropy were investigated with a series of model simulations based on the shallow unit solution. The anisotropy sensitivity analysis suggests that increased anisotropy ratio or decreased axial permeability has a significant impact on the velocity profile at the lower boundary, especially at high values of the anisotropy ratio. This result may increase estimates of SVE removal rates for contaminants located at the interface of the lower boundary, typical of chlorinated solvent contamination.

  13. Intestinal Membrane Permeability and Hypersensitivity In the Irritable Bowel Syndrome

    PubMed Central

    Zhou, QiQi; Zhang, Buyi; Verne, G. Nicholas

    2009-01-01

    Irritable bowel syndrome (IBS) is a common gastrointestinal disorder in which the underlying pathophysiology is poorly understood; however, increased intestinal permeability in diarrhea-predominant IBS patients has been reported. Here we demonstrate diarrhea-predominant IBS patients (D-IBS) that display increased intestinal permeability. We have also found that increased intestinal membrane permeability is associated with visceral and thermal hypersensitivity in this subset of D-IBS patients. We evaluated 54 D-IBS patients and 22 controls for intestinal membrane permeability using the lactulose / mannitol method. All subjects ingested 5 g laclulose and 2 g mannitol in 100 ml of water after which their urine was collected. We also evaluated the mean mechanical visual analogue (MVAS) pain rating to nociceptive thermal and visceral stimulation in all subjects. All study participants also completed the FBDSI scale. Approximately 39% of diarrhea-predominant IBS patients have increased intestinal membrane permeability as measured by the lactulose / mannitol ratio. These IBS patients also demonstrated higher M-VAS pain intensity reading scale. Interestingly, the IBS patients with hypersensitivity and increased intestinal permeability had a higher FBDSI score (100.8±5.4) compared to IBS patients with normal membrane permeability and sensitivity (51.6±12.7) and controls (6.1 ± 5.6) (p<0.001). A subset of D-IBS patients have increased intestinal membrane permeability that is associated with an increased FBDSI score and increased hypersensitivity to visceral and thermal nociceptive pain stimuli. Thus, increased intestinal membrane permeability in D-IBS patients may lead to more severe IBS symptoms and hypersensitivity to somatic and visceral stimuli. PMID:19595511

  14. Patterns of effective permeability of leaf cuticles to acids

    SciTech Connect

    Hauser, H.D.; Walters, K.D.; Berg, V.S. )

    1993-01-01

    Plants in the field are frequently exposed to anthropogenic acid precipitation with pH values of 4 and below. For the acid to directly affect leaf tissues, it must pass through the leaf cuticle, but little is known about the permeability of cuticles to protons, of about the effect of different anions on this permeability. We investigated the movement of protons through isolated astomatous leaf cuticles of grapefruit (Citrus x paradisi Macfady.), rough lemon (Citrus limon [L.] Burm. fils cv Ponderosa), and pear (Pyrus communis L.) using hydrochloric, sulfuric, and nitric acids. Cuticles were enzymically isolated from leaves and placed in a diffusion apparatus with pH 4 acid on the morphological outer surface of the cuticle and degassed distilled water on the inner surface. Changes in pH of the solution on the inner surface were used to determine rates of effective permeability of the cuticles to the protons of these acids. Most cuticles exhibited an initial low permeability, lasting hours to days, then after a short transition displayed a significant higher permeability, which persisted until equilibrium was approached. The change in effective permeability appears to be reversible. Effective permeabilities were higher for sulfuric acid than for the others. A model of the movement of protons through the cuticle is presented, proposing that dissociated acid groups in channels within the cutin are first protonated by the acid, accounting for the low initial effective permeability; then protons pass freely through the channels, resulting in a higher effective permeability. 26 refs., 6 figs., 2 tabs.

  15. Correlations for the diffusivity and permeability for Devonian shale

    SciTech Connect

    Cannon, T.J.; Johnston, D.A.; Fogler, H.S.; Schultz, J.S.

    1980-07-01

    Energy extraction from oil shale is a major facet of the expanding synthetic fuels program. In situ retorting of oil shale presents a method of recovering a portion of that stored energy content by inducing a flame front through the shale. Diffusivity and permeability are measures of the ease of movement of air toward the flame front and product gases away from the front. This study reports on measurements of diffusivity and permeability at seven depths within and below the Antrim shale for unretorted and retorted cores. The threshold pressures were also measured and compared to the predictions given by correlations. Finally, correlations were developed between the diffusivity, permeability and other physical properties.

  16. Effects of aspirin on gastroduodenal permeability in alcoholics and controls.

    PubMed

    Farhadi, Ashkan; Keshavarzian, Ali; Kwasny, Mary J; Shaikh, Maliha; Fogg, Louis; Lau, Cynthia; Fields, Jeremy Z; Forsyth, Christopher B

    2010-08-01

    Alcohol and nonsteroidal anti-inflammatory drugs are noxious agents that can disrupt the integrity of the gastroduodenal mucosal and damage the epithelial barrier and lead to increased gastroduodenal permeability. Moreover, it is not uncommon that patients are exposed to these two barrier stressors at the same time. It is thus important to know how simultaneous exposure affects the gastroduodenal barrier, and acquiring that knowledge was the goal of this study. We used a method that has been widely used for the assessment of injury to the gastroduodenal barrier induced by these noxious agents-measurement of gastroduodenal permeability as indicated by urinary excretion of ingested sucrose. We used gas chromatography to measure the amount of sucrose excreted in the urine over the 5-12h after ingestion of a bolus of sucrose. The 148 participants in the study included 92 alcoholics and 56 healthy controls. All study subjects had a baseline permeability test. To determine whether addition of a second noxious agent, in addition to chronic alcohol, further decreases gastroduodenal barrier integrity, a subset of 118 study subjects participated in another permeability test in which they were exposed to aspirin. For this test, participants ingested 1,300 mg aspirin twice, 12 and 1h before the final permeability test. The baseline permeability test showed that alcoholics have significantly higher gastroduodenal permeability than controls. Aspirin caused a significant within-group absolute increase in gastroduodenal permeability in both alcoholics and controls (+7.72%, P=.003 and +2.25%, P=.011, respectively), but the magnitude of these increases was not significantly different from each other. Baseline permeability did vary by gender, self-reported illegal drug use, and employment type. The extent of the permeability increase after aspirin ingestion varied with illegal drug use and recruitment site (a surrogate marker of socioeconomic status). Our data show that alcoholics

  17. MRI of Blood–Brain Barrier Permeability in Cerebral Ischemia

    PubMed Central

    Ewing, James R.; Chopp, Michael

    2013-01-01

    Quantitative measurement of blood–brain barrier (BBB) permeability using MRI and its application to cerebral ischemia are reviewed. Measurement of BBB permeability using MRI has been employed to evaluate ischemic damage during acute and subacute phases of stroke and to predict hemorrhagic transformation. There is also an emerging interest on the development and use of MRI to monitor vascular structural changes and angiogenesis during stroke recovery. In this review, we describe MRI BBB permeability and susceptibility-weighted MRI measurements and its applications to evaluate ischemic damage during the acute and subacute phases of stroke and vascular remodeling during stroke recovery. PMID:23997835

  18. Fractal Analysis of Stress Sensitivity of Permeability in Porous Media

    NASA Astrophysics Data System (ADS)

    Tan, Xiao-Hua; Li, Xiao-Ping; Liu, Jian-Yi; Zhang, Lie-Hui; Cai, Jianchao

    2015-12-01

    A permeability model for porous media considering the stress sensitivity is derived based on mechanics of materials and the fractal characteristics of solid cluster size distribution. The permeability of porous media considering the stress sensitivity is related to solid cluster fractal dimension, solid cluster fractal tortuosity dimension, solid cluster minimum diameter and solid cluster maximum diameter, Young's modulus, Poisson's ratio, as well as power index. Every parameter has clear physical meaning without the use of empirical constants. The model predictions of permeability show good agreement with those obtained by the available experimental expression. The proposed model may be conducible to a better understanding of the mechanism for flow in elastic porous media.

  19. Measurement of the intestinal permeability in chronic kidney disease

    PubMed Central

    Terpstra, Matty L; Singh, Ramandeep; Geerlings, Suzanne E; Bemelman, Frederike J

    2016-01-01

    AIM: To evaluate methods measuring the intestinal per-meability in chronic kidney disease (CKD) and clarify whether there is an increased intestinal permeability in CKD. METHODS: We reviewed the literature in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol and performed a systematic literature search through MEDline and EMBASE. All controlled trials and cohort studies using non-invasive methods to assess intestinal permeability in CKD patients were included. Excluded were: Conference abstracts and studies including patients younger than 18 years or animals. From the included studies we summarized the used methods and their advantages and disadvantages. For the comparison of their results we divided the included studies in two categories based on their included patient population, either assessing the intestinal permeability in mild to moderate CKD patients or in end stage renal disease (ESRD) patients. Results were graphically displayed in two plots, one comparing the intestinal permeability in mild to moderate CKD patients to healthy controls and one comparing the intestinal permeability in ESRD patients to healthy controls. RESULTS: From the 480 identified reports, 15 met our inclusion criteria. Methods that were used to assess the intestinal permeability varied from markers measured in plasma to methods based on calculating the urinary excretion of an orally administered test substance. None of the applied methods has been validated in CKD patients and the influence of decreased renal function on the different methods remains unclear to a certain extent. Methods that seem the least likely to be influenced by decreased renal function are the quantitative PCR (qPCR) for bacterial DNA in blood and D-lactate. Considering the results published by the included studies; the studies including patients with mild to moderate CKD conducted conflicting results. Some studies did report an increase in intestinal

  20. Quantifying the complex permittivity and permeability of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Yao, B. M.; Gui, Y. S.; Worden, M.; Hegmann, T.; Xing, M.; Chen, X. S.; Lu, W.; Wroczynskyj, Y.; van Lierop, J.; Hu, C.-M.

    2015-04-01

    The complex permittivity and permeability of superparamagnetic iron-oxide nanoparticles has been quantified using a circular waveguide assembly with a static magnetic field to align the nanoparticle's magnetization. The high sensitivity of the measurement provides the precise resonant feature of nanoparticles. The complex permeability in the vicinity of ferromagnetic resonance is in agreement with the nanoparticle's measured magnetization via conventional magnetometry. A rigorous and self-consistent measure of complex permittivities and permeabilities of nanoparticles is crucial to ascertain accurately the dielectric behaviour as well as the frequency response of nanoparticle magnetization, necessary ingredients when designing and optimizing magnetic nanoparticles for biomedical applications.

  1. Preasymptotic hydrodynamic dispersion as a quantitative probe of permeability.

    PubMed

    Brosten, Tyler R; Vogt, Sarah J; Seymour, Joseph D; Codd, Sarah L; Maier, Robert S

    2012-04-01

    We interpret a generalized short-time expansion of stochastic hydrodynamic dispersion dynamics in the case of small Reynolds number flow through macroscopically homogenous permeable porous media to directly determine hydrodynamic permeability. The approach allows determination of hydrodynamic permeability from pulsed field gradient spin-echo nuclear magnetic resonance measurement of the short-time effective hydrodynamic dispersion coefficient. The analytical expansion of asymptotic dynamics agrees with experimental NMR data and lattice Boltzmann simulation of hydrodynamic dispersion in consolidated random sphere pack media. PMID:22680531

  2. Timescales for permeability reduction and strength recovery in densifying magma

    NASA Astrophysics Data System (ADS)

    Heap, M. J.; Farquharson, J. I.; Wadsworth, F. B.; Kolzenburg, S.; Russell, J. K.

    2015-11-01

    Transitions between effusive and explosive behaviour are routine for many active volcanoes. The permeability of the system, thought to help regulate eruption style, is likely therefore in a state of constant change. Viscous densification of conduit magma during effusive periods, resulting in physical and textural property modifications, may reduce permeability to that preparatory for an explosive eruption. We present here a study designed to estimate timescales of permeability reduction and strength recovery during viscous magma densification by coupling measurements of permeability and strength (using samples from a suite of variably welded, yet compositionally identical, volcanic deposits) with a rheological model for viscous compaction and a micromechanical model, respectively. Bayesian Information Criterion analysis confirms that our porosity-permeability data are best described by two power laws that intersect at a porosity of 0.155 (the "changepoint" porosity). Above and below this changepoint, the permeability-porosity relationship has a power law exponent of 8.8 and 1.0, respectively. Quantitative pore size analysis and micromechanical modelling highlight that the high exponent above the changepoint is due to the closure of wide (∼200-300 μm) inter-granular flow channels during viscous densification and that, below the changepoint, the fluid pathway is restricted to narrow (∼50 μm) channels. The large number of such narrow channels allows porosity loss without considerable permeability reduction, explaining the switch to a lower exponent. Using these data, our modelling predicts a permeability reduction of four orders of magnitude (for volcanically relevant temperatures and depths) and a strength increase of a factor of six on the order of days to weeks. This discrepancy suggests that, while the viscous densification of conduit magma will inhibit outgassing efficiency over time, the regions of the conduit prone to fracturing, such as the margins, will

  3. Instrumentation for Measurement of Gas Permeability of Polymeric Membranes

    NASA Technical Reports Server (NTRS)

    Upchurch, Billy T.; Wood, George M.; Brown, Kenneth G.; Burns, Karen S.

    1993-01-01

    A mass spectrometric 'Dynamic Delta' method for the measurement of gas permeability of polymeric membranes has been developed. The method is universally applicable for measurement of the permeability of any gas through polymeric membrane materials. The usual large sample size of more than 100 square centimeters required for other methods is not necessary for this new method which requires a size less than one square centimeter. The new method should fulfill requirements and find applicability for industrial materials such as food packaging, contact lenses and other commercial materials where gas permeability or permselectivity properties are important.

  4. Effects of Aspirin on Gastroduodenal Permeability in Alcoholics and Controls

    PubMed Central

    Farhadi, Ashkan; Keshavarzian, Ali; Kwasny, Mary J.; Shaikh, Maliha; Fogg, Louis; Lau, Cynthia; Fields, Jeremy Z.; Forsyth, Christopher B.

    2010-01-01

    Alcohol and non-steroidal anti-inflammatory drugs (NSAIDS) are noxious agents that can disrupt the integrity of the gastroduodenal mucosal and damage the epithelial barrier, and lead to increased gastroduodenal permeability. Moreover, it is not uncommon that patients are exposed to these two barrier stressors at the same time. It is thus important to know how simultaneous exposure affects the gastroduodenal barrier, and acquiring that knowledge was the goal of this study. We used a method that has been widely used for the assessment of injury to the gastroduodenal barrier induced by these noxious agents – measurement of gastroduodenal permeability as indicated by urinary excretion of ingested sucrose. We used gas chromatography to measure the amount of sucrose excreted in the urine over the 5–12 h following ingestion of a bolus of sucrose. The 148 participants in the study included 92 alcoholics and 56 healthy controls. All study subjects had a baseline permeability test. To determine whether addition of a second noxious agent, in addition to chronic alcohol, further decreases gastroduodenal barrier integrity, a subset of 118 study subjects participated in another permeability test in which they were exposed to aspirin. For this test, participants ingested 1300 mg aspirin twice, 12 hours and 1 hour before the final permeability test. The baseline permeability test showed that alcoholics have significantly higher gastroduodenal permeability than controls. Aspirin caused a significant within group absolute increase in gastroduodenal permeability in both alcoholics and controls (+7.72%, p=0.003 and +2.25%, p = 0.011, respectively) but the magnitude of these increases were not significantly different from each other. Baseline permeability did vary by gender, self-reported illegal drug use, and employment type. The extent of the permeability increase after aspirin ingestion varied with illegal drug use and recruitment site (a surrogate marker of socioeconomic status

  5. Canine RBC osmotic tolerance and membrane permeability.

    PubMed

    Liu, J; Christian, J A; Critser, J K

    2002-06-01

    The objective of this study was to determine the cryobiological characteristics of canine red blood cells (RBC). These included the hydraulic conductivity (L(p)), the permeability coefficients (P(s)) of common cryoprotectant agents (CPAs), the associated reflection coefficient (sigma), the activation energies (E(a)) of L(p) and P(s) and the osmotic tolerance limits. By using a stopped-flow apparatus, the changes of fluorescence intensity emitted by intracellularly entrapped 5-carboxyfluorescein diacetate (CFDA) were recorded when cells were experiencing osmotic volume changes. After the determination of the relationship between fluorescence intensity and cell volume, cell volume changes were calculated. These volume changes were used in three-parameter fitting calculations to determine the values of L(p), P(s), and sigma for common CPAs. These volume measurements and data analyses were repeated at three different temperatures (22, 14, 7 degrees C). Using the Arrhenius equation, the activation energies of L(p) and P(s) in the presence of CPAs were determined. The osmotic tolerance limits for canine RBC were determined by measuring the percentage of free hemoglobin in NaCl solutions with various osmolalities compared to that released by RBC incubated in double distilled water. The upper and lower osmotic tolerance limits were found to be 150mOsm (1.67V(iso)) and 1200mOsm (0.45V(iso)), respectively. These parameters were then used to calculate the amount of non-permeating solute needed to keep cell volume excursions within the osmotic tolerance limits during CPA addition and removal. PMID:12237091

  6. Composites with tuned effective magnetic permeability

    NASA Astrophysics Data System (ADS)

    Amirkhizi, Alireza V.; Nemat-Nasser, Sia

    2007-07-01

    Pendry et al. [J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, IEEE Trans. Microwave Theory Tech. 47, 2075 (1999)] and Smith et al. [D. R. Smith, W. J. Padilla, D. C. Vier, S. C. Nemat-Nasser, and S. Schultz, Phys. Rev. Lett. 84, 4184 (2000)] have shown that the effective magnetic permeability, μ, of free space can be rendered negative over a certain frequency range by a periodic arrangement of very thin conductors with suitable magnetic resonance properties, the so-called split-ring resonators. Because of its rather bulky architecture, this structure does not lend itself to a proper integration into a reasonably thin real composite structural panel. To remedy this fundamental barrier, we invented a new magnetic resonator consisting of very thin folded plates that are suitably nested within one another to form folded-doubled resonators (FDRs) that can be integrated into an actual composite panel. Measurements, using a focused beam electromagnetic characterization system combined with time-domain numerical simulations of the reflection and transmission coefficients of such a composite slab have revealed that indeed the composite has a negative μ over a frequency range of about 9.1-9.35 GHz [S. Nemat-Nasser, S. C. Nemat-Nasser, T. A. Plaisted, A. Starr, and A. Vakil Amirkhizi, in Biomimetics: Biologically Inspired Technologies, edited by Y. Bar Cohen (CRC Press, Boca Raton, FL, 2006)]. Thus, it has become possible to construct a structural composite panel with negative index of refraction by simultaneously creating negative effective ɛ and μ [V. G. Veselago, Sov. Phys. Usp. 10, 509 (1968); R. A. Shelby, D. R. Smith, and S. Schultz, Science 292, 77 (2001); A. F. Starr, P. M. Rye, D. R. Smith, and S. Nemat-Nasser, Phys. Rev. B 70, 113102 (2004)].

  7. Transverse chemotactic migration of bacteria from high to low permeability regions in a dual permeability microfluidic device.

    PubMed

    Singh, Rajveer; Olson, Mira Stone

    2012-03-20

    Low permeability regions such as clay lenses are difficult to remediate using conventional treatment methods. Bacterial chemotaxis (directed migration toward a contaminant source) may be helpful in enhancing bioremediation of such contaminated sites. This study experimentally simulates a two-dimensional dual-permeability groundwater contamination scenario using a microfluidic device (MFD) and evaluates transverse chemotactic migration of bacteria from high to low permeability regions under various flow velocities. Chemotaxis of Escherichia coli (E. coli) HCB33 to the chemoattractant dl-aspartic acid was quantified in terms of change in total bacterial counts in pore throats in low permeability regions containing attractant. An increase in total bacterial counts, ranging from 1.09 to 1.74 times, was observed in low permeability regions in experiments under chemotactic conditions. Experiments with no attractant showed no increase in total bacterial counts in low permeability regions. A large increase in bacterial counts in the pore throats just outside the low permeability region was also observed in chemotaxis experiments. The bacterial chemotactic response was observed to decrease linearly with increase in flow velocity, with no observed response at the highest flow velocity (Darcy velocity = 0.22 mm/s), where chemotaxis was offset by advective flow.

  8. Experimental Measurement of Vertical and Horizontal Permeability of Caprocks from the Krechba Field, Algeria and the Controls on their Permeability

    NASA Astrophysics Data System (ADS)

    Armitage, P. J.; Faulkner, D. R.; Worden, R. H.; Illife, J.

    2008-12-01

    Caprock properties play a crucial role in determining the seal capacity of a structure and so are important during exploration, appraisal and field development. Less attention has been paid to caprocks than reservoirs since if petroleum is present, then the seal must be working. However, injection of CO2 to underlying reservoirs will alter the reservoir conditions from those against which the caprock was previously effective. Increased knowledge of the petrological and petrophysical characteristics of caprocks is required in order to lay a foundation to predict the effect of the altered conditions caused by CO2 injection. Vertical (kv) and horizontal (kh) permeability were measured experimentally across a range of effective pressures for an unusually coarse grained, heterogeneous caprock (siltstone) to a natural gas reservoir and current CO2 storage reservoir, from the Krechba Field, Algeria. Permeabilities as low as 10-23m2 were recorded and were in the range of, or lower than typical fine grained siliciclastic caprock lithologies. The permeability was analysed in conjunction with mercury injection porosimetry data, and textural and mineralogical data from traditional light microscopy, backscatter secondary electron microscopy (BSEM) and cathode luminescence (CL) techniques as well as new QEMSCAN techniques to elucidate the controls on permeability. As predicted and measured by previous experimental work on fine grained siliciclastic lithologies, permeability is effectively controlled by porosity, pore size distribution and clay fraction. Permeability generally decreases with decreasing porosity and poresize distribution and increasing clay content. However, scatter in the trends was caused by heterogeneity of the sample leading to large kv and kh ratios. Primary depositional features led to layers of relatively low and high permeability in the samples, with kv controlled by the lowest permeability layer, and kh controlled by highest permeability layer. Thus kh

  9. Probing permeability and microstructure: Unravelling the role of a low-permeability dome on the explosivity of Merapi (Indonesia)

    NASA Astrophysics Data System (ADS)

    Kushnir, Alexandra R. L.; Martel, Caroline; Bourdier, Jean-Louis; Heap, Michael J.; Reuschlé, Thierry; Erdmann, Saskia; Komorowski, Jean-Christophe; Cholik, Noer

    2016-04-01

    Low permeability dome rocks may contribute to conduit overpressure development in volcanic systems, indirectly abetting explosive activity. The permeability of dome-forming rocks is primarily controlled by the volume, type (vesicles and/or microcracks), and connectivity of the void space present. Here we investigate the permeability-porosity relationship of dome-forming rocks and pumice clasts from Merapi's 1888 to 2013 eruptions and assess their possible role in eruptive processes, with particular emphasis on the 2010 paroxysmal eruption. Rocks are divided into three simple field classifications common to all eruptions: Type 1 samples have low bulk density and are pumiceous in texture; Type 2 samples, ubiquitous to the 2010 eruption, are dark grey to black in hand sample and vary greatly in vesicularity; and Type 3 samples are weakly vesicular, light grey in hand sample, and are the only samples that contain cristobalite. Type 2 and Type 3 rocks are present in all eruptions and their permeability and porosity data define similar power law relationships, whereas data for Type 1 samples are clearly discontinuous from these trends. A compilation of permeability and porosity data for andesites and basaltic andesites with published values highlights two microstructural transitions that exert control on permeability, confirmed by modified Bayesian Information Criterion (BIC) analysis. Permeability is microcrack- and diktytaxitic-controlled at connected porosities, φc, < 10.5 vol.%; vesicle- and microcrack-controlled at 10.5 < φc < 31 vol.%; and likely vesicle-controlled for φc > 31 vol.%. Type 3 basaltic andesites, the least permeable of the measured samples and therefore the most likely to have originated in the uppermost low-permeability dome, are identified as relicts of terminal domes (the last dome extruded prior to quiescence). Cristobalite commonly found in the voids of Type 3 blocks may not contribute significantly to the reduction of the permeability of

  10. TREATMENT OF INORGANIC CONTAMINANTS USING PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Permeable reactive barriers are an emerging alternative to traditional pump and treat systems for groundwater remediation. This technique has progressed rapidly over the past decade from laboratory bench-scale studies to full-scale implementation. Laboratory studies indicate the ...

  11. Xenon NMR measurements of permeability and tortuosity in reservoir rocks.

    PubMed

    Wang, Ruopeng; Pavlin, Tina; Rosen, Matthew Scott; Mair, Ross William; Cory, David G; Walsworth, Ronald Lee

    2005-02-01

    In this work we present measurements of permeability, effective porosity and tortuosity on a variety of rock samples using NMR/MRI of thermal and laser-polarized gas. Permeability and effective porosity are measured simultaneously using MRI to monitor the inflow of laser-polarized xenon into the rock core. Tortuosity is determined from measurements of the time-dependent diffusion coefficient using thermal xenon in sealed samples. The initial results from a limited number of rocks indicate inverse correlations between tortuosity and both effective porosity and permeability. Further studies to widen the number of types of rocks studied may eventually aid in explaining the poorly understood connection between permeability and tortuosity of rock cores. PMID:15833638

  12. Research Update from EPA Permeable Parking Lot in Edison, NJ

    EPA Science Inventory

    Communities are increasingly installing green infrastructure stormwater control measures (SCMs) to reduce pollutant loads associated with stormwater runoff. Permeable pavement is a SCM that has limited research on working-scale, side-by-side performance of different pavement sur...

  13. Porosity, permeability, and their relationship in granite, basalt, and tuff

    SciTech Connect

    Not Available

    1983-04-01

    This report discusses the porosity, storage, and permeability of fractured (mainly crystalline) rock types proposed as host rock for nuclear waste repositories. The emphasis is on the inter-relationships of these properties, but a number of reported measurements are included as well. The porosity of rock is shown to consist of fracture porosity and matrix porosity; techniques are described for determining the total interconnected porosity through both laboratory and field measurement. Permeability coefficient, as obtained by experiments ranging from laboratory to crustal scale, is discussed. Finally, the problem of determining the relationship between porosity and permeability is discussed. There is no simple, all encompassing relationship that describes the dependence of permeability upon porosity. However, two particular cases have been successfully analyzed: flow through a single rough fracture, and flow through isotropic porous rock. These two cases are discussed in this report.

  14. Correlation of Three Techniques for Determining Soil Permeability

    ERIC Educational Resources Information Center

    Winneberger, John T.

    1974-01-01

    Discusses problems of acquiring adequate results when measuring for soil permeability. Correlates three relatively simple techniques that could be helpful to the inexperienced technician dealing with septic tank practices. An appendix includes procedures for valid percolation tests. (MLB)

  15. The mitochondrial permeability transition from yeast to mammals

    PubMed Central

    Azzolin, Luca; von Stockum, Sophia; Basso, Emy; Petronilli, Valeria; Forte, Michael A.; Bernardi, Paolo

    2010-01-01

    Regulated permeability changes have been detected in mitochondria across species. We review here their key features, with the goal of assessing whether a “permeability transition” similar to that observed in higher eukaryotes is present in other species. The recent discoveries (i) that treatment with cyclosporin A unmasks an inhibitory site for Pi [Basso et al. (2008) J. Biol Chem. 283, 26307–26311], the classical inhibitor of the permeability transition of yeast; and (ii) that under proper experimental conditions a matrix Ca2+-dependence can be demonstrated in yeast as well [Yamada et al. (2009) Biochim. Biophys. Acta 1787, 1486–1491] suggest that the mitochondrial permeability transition has been conserved during evolution. PMID:20398660

  16. Preliminary relative permeability estimates of methanehydrate-bearing sand

    SciTech Connect

    Seol, Yongkoo; Kneafsey, Timothy J.; Tomutsa, Liviu; Moridis,George J.

    2006-05-08

    The relative permeability to fluids in hydrate-bearing sediments is an important parameter for predicting natural gas production from gas hydrate reservoirs. We estimated the relative permeability parameters (van Genuchten alpha and m) in a hydrate-bearing sand by means of inverse modeling, which involved matching water saturation predictions with observations from a controlled waterflood experiment. We used x-ray computed tomography (CT) scanning to determine both the porosity and the hydrate and aqueous phase saturation distributions in the samples. X-ray CT images showed that hydrate and aqueous phase saturations are non-uniform, and that water flow focuses in regions of lower hydrate saturation. The relative permeability parameters were estimated at two locations in each sample. Differences between the estimated parameter sets at the two locations were attributed to heterogeneity in the hydrate saturation. Better estimates of the relative permeability parameters require further refinement of the experimental design, and better description of heterogeneity in the numerical inversions.

  17. Air permeability and trapped-air content in two soils

    USGS Publications Warehouse

    Stonestrom, D.A.; Rubin, J.

    1989-01-01

    To improve understanding of hysteretic air permeability relations, a need exists for data on the water content dependence of air permeability, matric pressure, and air trapping (especially for wetting-drying cycles). To obtain these data, a special instrument was designed. The instrument is a combination of a gas permeameter (for air permeability determination), a suction plate apparatus (for retentivity curve determination), and an air pycnometer (for trapped-air-volume determination). This design allowed values of air permeability, matric pressure, and air trapping to be codetermined, i.e., determined at the same values of water content using the same sample and the same inflow-outflow boundaries. Such data were obtained for two nonswelling soils. -from Authors

  18. Towards Polymer-Based Capsules with Drastically Reduced Controlled Permeability

    NASA Astrophysics Data System (ADS)

    Andreeva, Daria V.; Sukhorukov, Gleb B.

    Small molecules (dyes, therapeutics, etc.) could be easily handled, stored, delivered, and released by polyelectrolyte capsules. To make the polyelectrolyte capsule more efficient for small molecule encapsulation, capsule permeability should be significantly decreased. Here, we demonstrate the possibility to entrap water-soluble molecular species into polyelectrolyte capsules modified by a low permeable dense polymer (polypyrrole). Possible future areas in PE capsule application as carriers for gases and volatiles in the pharmaceutical, food, and gases industry, agriculture and cosmetology are discussed.

  19. Influence of Subslab Aggregate Permeability of SSV Performance

    SciTech Connect

    Gadgil, A.J.; Bonnefous, Y.C.; Fisk, W.J.; Prill, R.J.; Nematollahi, A.

    1991-09-01

    The effectiveness of the technique of subslab ventilation (SSV) for limiting radon entry into basements was investigated through complementary experimentation and numerical modeling. Determination of the impact of subslab aggregate permeability on SSV performance was a primary objective. Subslab pressure fields resulting from SSV were measured in six well-characterized basements, each with a different combination of soil and aggregate permeability. The relationship between air velocity and pressure gradient within the three types of aggregate installed beneath the basement slabs was measured in the laboratory. A new numerical model of SSV was developed and verified with the field data. This model simulates non-Darcy flow in the aggregate. We demonstrate that non-Darcy effects significantly impact SSV performance. Field data and numerical simulations indicate that increasing the aggregate permeability within the investigated range of 2 x 10{sup -8} m{sup 2} to 3 x 10{sup -7} m{sup 2} substantially improves the extension of the subslab pressure field due to SSV operation. Subslab pressure field extension also improves as soil permeability decreases between 10{sup -9} m{sup 2} and 10{sup -10} m{sup 2}. With a slab-wall gap thickness of 1 mm and the range of aggregate permeability investigated, further reductions in soil permeability do not significantly improve the subslab pressure field extension. Sealing of cracks in the slab and excavation of a small pit where the SSV pipe penetrates the slab also dramatically improve this pressure field extension. A large ratio of aggregate permeability to soil permeability reduces the need for large depressurizations at the SSV pit. Our findings are consistent with the results of prior field studies; however, our understanding of SSV is improved and the dependence of SSV performance on the relevant parameters can now be quantified with the model.

  20. Development of optimized, graded-permeability axial groove heat pipes

    NASA Technical Reports Server (NTRS)

    Kapolnek, Michael R.; Holmes, H. Rolland

    1988-01-01

    Heat pipe performance can usually be improved by uniformly varying or grading wick permeability from end to end. A unique and cost effective method for grading the permeability of an axial groove heat pipe is described - selective chemical etching of the pipe casing. This method was developed and demonstrated on a proof-of-concept test article. The process improved the test article's performance by 50 percent. Further improvement is possible through the use of optimally etched grooves.

  1. Hybrid green permeable pave with hexagonal modular pavement systems

    NASA Astrophysics Data System (ADS)

    Rashid, M. A.; Abustan, I.; Hamzah, M. O.

    2013-06-01

    Modular permeable pavements are alternatives to the traditional impervious asphalt and concrete pavements. Pervious pore spaces in the surface allow for water to infiltrate into the pavement during rainfall events. As of their ability to allow water to quickly infiltrate through the surface, modular permeable pavements allow for reductions in runoff quantity and peak runoff rates. Even in areas where the underlying soil is not ideal for modular permeable pavements, the installation of under drains has still been shown to reflect these reductions. Modular permeable pavements have been regarded as an effective tool in helping with stormwater control. It also affects the water quality of stormwater runoff. Places using modular permeable pavement has been shown to cause a significant decrease in several heavy metal concentrations as well as suspended solids. Removal rates are dependent upon the material used for the pavers and sub-base material, as well as the surface void space. Most heavy metals are captured in the top layers of the void space fill media. Permeable pavements are now considered an effective BMP for reducing stormwater runoff volume and peak flow. This study examines the extent to which such combined pavement systems are capable of handling load from the vehicles. Experimental investigation were undertaken to quantify the compressive characteristics of the modular. Results shows impressive results of achieving high safety factor for daily life vehicles.

  2. Permeability of fault gouge under confining pressure and shear stress.

    USGS Publications Warehouse

    Morrow, C.A.; Shi, L.Q.; Byerlee, J.D.

    1984-01-01

    The permeability of both clay-rich and non-clay gouges, as well as several pure clays, was studied as a function of confining pressures from 5 to 200 MPa and shear strain to 10. Permeability ranged over 4 orders of magnitude, from around 10-22 to 10-18 m2 (1 darcy = 0.987 X 10-12 m2). Grain size was an important factor in determining permeability, particularly for the clay-rich samples. The permeabilities of the non-clay samples were not significantly different than those of the clays. Strength of the saturated samples under drained (low pore pressure) conditions did not correlate with high or low permeability. However, the low permeabilities of these gouges could be a factor in the measured low shear stresses along fault regions if excess pore pressures were created as a result of shearing or compaction, and this pressure was unable to dissipate through a thick section of the material.-from Authors

  3. Influence of Relict Joints on Permeability of Residual Soil

    NASA Astrophysics Data System (ADS)

    Talib, Z. A.; Kassim, A.; Yunusa, G. H.

    2016-07-01

    Weathering process of granitic material results in the formation of relict joint in lateritic layer of the weathering profile. The number and arrangements of the relict joints affects the permeability of the residual soil which invariably affects water flow and suction distribution in the residual soil. Although the permeability of residual soil without a relict joint can be determined using standard permeability test, it is difficult to be measured when a relict joint is incorporated due to limitation of size and area of the standard equipment. Hence, modified permeability test equipment is introduced in this study. Two arrangement of the relict joint in the equipment were considered. In the first arrangement one relict joint with various spacing were tested while the orientation and spacing of the relict joint were tested using two relict joints in the second arrangement. The results obtained shows that the permeability of the residual soil due to one and two relict joint varies by two orders of magnitude. Therefore, the number and spacing of relict joints modified the permeability of residual soil.

  4. Regulation of AQP0 water permeability is enhanced by cooperativity.

    PubMed

    Németh-Cahalan, Karin L; Clemens, Daniel M; Hall, James E

    2013-03-01

    Aquaporin 0 (AQP0), essential for lens clarity, is a tetrameric protein composed of four identical monomers, each of which has its own water pore. The water permeability of AQP0 expressed in Xenopus laevis oocytes can be approximately doubled by changes in calcium concentration or pH. Although each monomer pore functions as a water channel, under certain conditions the pores act cooperatively. In other words, the tetramer is the functional unit. In this paper, we show that changes in external pH and calcium can induce an increase in water permeability that exhibits either a positive cooperativity switch-like increase in water permeability or an increase in water permeability in which each monomer acts independently and additively. Because the concentrations of calcium and hydrogen ions increase toward the center of the lens, a concentration signal could trigger a regulatory change in AQP0 water permeability. It thus seems plausible that the cooperative modes of water permeability regulation by AQP0 tetramers mediated by decreased pH and elevated calcium are the physiologically important ones in the living lens. PMID:23440275

  5. Permeability controls in the Santana Tuff, Trans-Pecos Texas

    SciTech Connect

    Smyth, R.C.; Sharp, J.M. Jr. . Dept. of Geological Sciences)

    1993-02-01

    The Santana Tuff is a poorly to densely welded rhyolitic ash-flow tuff that erupted from the Sierra Rica caldera complex in Chihuahua, Mexico, 27.8 m.y. ago. The portion of the Santana Tuff examined in this study crops out over a 125-km[sup 2] area in the Big Bend Ranch State Natural Area in Trans-Pecos Texas. A review of recent literature has revealed the need to incorporate realistic values for permeability due to fracture spacing into groundwater models. Permeability/porosity relationship for fracture skins and unaltered tuff are significant to problems of solute transport. Permeability measurements of tuff samples vary over four orders of magnitude. The most densely welded samples have the lowest permeability. The least densely welded ones have the highest permeability. However, effective permeabilities of the differentially welded layers are quite different if fractures are considered. The spacing of cooling fractures in poorly to densely welded layers of the Santana Tuff also varies considerably. Degree of welding of the different Santana Tuff units has been quantified by length-to-width ratios (flattening) of pumice fragments. Lognormally distributed fracture spacing measurements correlate directly with the degree of welding. Rose diagrams and stereonets indicate that fracture orientations are not always random, as might be inferred from a cooling origin, but may have preferred orientation patterns.

  6. The diffusion-active permeable reactive barrier.

    PubMed

    Schwarz, Alex O; Rittmann, Bruce E

    2010-03-01

    Using the biogeochemical model CCBATCH, which we expanded to include transport processes, we study a novel approach for the treatment of aquifers contaminated with toxic concentrations of metals, the diffusion-active permeable reactive barrier (DAPRB), which is based on generation of sulfide by Sulfate Reducing Bacteria (SRB) as the groundwater moves through a layered treatment zone. In the DAPRB, layers of low conductivity (low-K) containing reactive materials are intercalated between layers of high conductivity (high-K) that transport the groundwater across the barrier. Because diffusion dominates transport in the reactive layers, microbial communities can take advantage there of the chemical-gradient mechanism for protection from toxicants. The ideal sulfidic DAPRB design includes particulate organic matter (POM) and solid sulfate mineral inside the reactive (low-K) layer. This leads to sulfate reduction and the formation of sulfide ligands that complex with toxic metals, such as Zn(2+) in the high-K layer. We perform a theoretical biogeochemical analysis of the ideal configuration of a DAPRB for treatment of Zn-contaminated groundwater. Our analysis using the expanded CCBATCH confirms the gradient-resistance mechanism for bio-protection, with the ZnS bio-sink forming at the intersection of the Zn and sulfide plumes inside the high-K layers of the DAPRB. The detailed DAPRB analysis also shows that total alkalinity and pH distributions are representative footprints of the two key biogeochemical processes taking place, sulfidogenesis and Zn immobilization as sulfide mineral. This is so because these two reactions consume or produce acidic hydrogen and alkalinity. Additionally, because Zn immobilization is due to ZnS mineral precipitation, the ZnS mineral distribution is a good indicator for the bio-sink. Bio-sinks are located for the most part within the high-K layers, and their exact position depends on the relative magnitude of metal and sulfide fluxes. Finally

  7. Saturated permeability measurements on pumice and welded-tuffaceous materials

    SciTech Connect

    Reda, D.C.; Hadley, G.R.

    1985-12-31

    An experimental apparatus was designed and built to allow water-saturated permeabilities as low as 10{sup -18} m{sup 2} to be measured on cores of diameter 5 cm and length 10 cm under steady-state flow conditions. This same apparatus can also be utilized in a transient (pressure-decay) mode in order to measure permeabilities several orders of magnitude lower than the steady-state limit. Tests were conducted on samples of pumice, fractured welded tuff, and welded tuff, representing a permeability range of seven orders of magnitude. Based on present measurements and calculations, the following results were obtained: Liquid-saturated permeability of the pumice core from Mount St. Helens was 2.76 x 10{sup -12} m{sup 2}; the corresponding Ergun constant was 4.43 x 10{sup 11} kg/m{sup 4}. The ultimate compressive strength of this material was found to be greater than 1.8 MPa, but less than 3.6 MPa; liquid-saturated permeability of the unfractured welded-tuff core was 5.6 x 10{sup -19} m{sup 2}; liquid-saturated permeability for the fractured welded-tuff core was found to decay to 2 x 10{sup -18} m{sup 2} after long-time-scale exposures to continuous-flow and applied-load conditions, independent of the initial fracture state (open vs closed); with an initially closed (naturally existing) fracture, core permeability decreased by a factor of about 2 over a 200-h test period; with an initially open fracture, core permeability decreased by a factor of about 4 under the influence of a comparable load-time history to that experienced in the natural-fracture test; final core permeability was found to be reduced by an order of magnitude from its initial level during a total 700-h test period; and the final effective hydraulic fracture aperture was calculated to be 10{sup -6} m for both tests on the fractured welded-tuff core; the final effective fracture permeability was calculated to be 10{sup -13} m{sup 2}, five orders of magnitude greater than the matrix-material prmeability

  8. Relating tortuosity and permeability in microfractured and unfractured porous media

    NASA Astrophysics Data System (ADS)

    Tokan-Lawal, A.; Wang, W.; Prodanovic, M.

    2012-12-01

    Permeability estimates are key to any subsurface flow prediction. Several methods are available for estimating (relative) permeability either on Darcy scale (lab measurements) or on pore scale (numerical flow simulation, assuming pore space geometry is known). However, relative permeability measurements in particular can be time consuming, and there is a benefit in having a fast estimate. Thus, a number of permeability estimates are available based on the some known porous medium parameters. The famous Carman Kozeny (1937) model represents the pores as parallel tubes of length equal to the sample length and of a range of radii. This single phase permeability model developed for packings of equal spherical grains relates the absolute permeability to the tortuosity of the medium. Fractures or fracture networks, on the other hand, do not lend themselves to an analytical description akin to pores spaces in-between a packing of spheres. Thus far, the study of flow in fractures has for the most part been limited to fractures in rock with impermeable fractures. The simplest models, such as the cubic law, relate fracture permeability to its average aperture and model fracture as parallel planes which are insufficient to extend to multiphase displacement. In this study, we focus on correlating permeability with geometric tortuosity of both pore space and individual fluid phases for a wide variety of homogeneous as well as microfractured porous samples. We use a combination of lattice-Boltzmann simulation and the level set method based progressive-quasistatic (LSMPQS) algorithm to characterize the capillary dominated flow properties (capillary pressure-saturation and relative permeability-saturation relationships) of the matrix, and when present, the fracture, in samples of different compositions. At the same time, we use image analysis tools to characterize the connectivity and tortuosity of the pore space, as well as individual fluid phases at different saturations

  9. Some Recent Laboratory Measurements of Fault Zone Permeability

    NASA Astrophysics Data System (ADS)

    Morrow, C. A.; Lockner, D. A.

    2005-12-01

    The permeability of fault zone material is key to understanding fluid circulation and the role of pore fluids in earthquake generation and rupture dynamics. Permeability results of core samples from several scientific drillholes are presented, including new results from the SAFOD drillsite in California and the Chelungpu Fault in Taiwan. Permeability values at simulated in situ pressures range from 10-18 to 10-23 m2, a broad range reflecting differences in rock type, proximity to the fault (i.e., fault core, damage zone or country rock), and degree of interseismic healing and sealing. In addition to these natural characteristics, stress-relief and thermal cracking damage resulting from core retrieval will tend to increase the permeability of some of the deepest crystalline rock samples, although testing under in situ conditions can reduce these errors. Recently active fault rocks, with an interconnected network of fractures, tend toward the higher end of the permeability range, whereas fault rocks that have had time to heal through hydrothermal processes tend to have lower permeabilities. In addition, the permeability of borehole-derived core samples was found to be more sensitive to applied pressure than equivalent rocks obtained from surface outcrops because of weathering and other processes. Thus, permeability values of surface samples can not be adequately extrapolated to depth, highlighting the importance of deep drilling studies in determining in situ transport properties. Permeability studies also reveal the storage capacity of the fault rocks, an important parameter in the determination of excess fluid pressure potential. Storage capacity was found to be 10-10 to 10-11/Pa in the Chelungpu Fault cores. Typical down-hole permeability measurements are generally 1-2 orders of magnitude higher than laboratory-derived values because they sample joints and fractures in the damage zone that are larger in scale than the core samples. Consequently, most fluid flow at

  10. Theoretical studies of permeability inversion from seismoelectric logs

    NASA Astrophysics Data System (ADS)

    Hu, H.; Guan, W.; Zhao, W.

    2012-04-01

    Permeability is one of the most important parameters for evaluating the level of difficulty in oil and gas exploitation. A quick, continuous and accurate in-situ estimate of reservoir permeability is highly significant. Stoneley wave logs have been used to determine formation permeability (Tang and Cheng, 1996). However, the inversion errors of this method are too big in low-permeability formations, especially in high-porosity and low-permeability formations resulting from the high clay content in pores. In this study, we propose to invert permeability by using the full waveforms of seismoelectric logs with low frequencies. This method is based on the relationship of permeability with the ratio of the electric excitation intensity to the pressure field's (REP) with respect to the Stoneley wave in seismoelectric logs. By solving the governing equations for electrokinetic coupled wavefields in homogeneous fluid-saturated porous media (Pride, 1994), we calculate the full waveforms of the borehole seismoelectric wavefields excited by a point pressure source and investigate frequency-dependent excitation intensities of the mode waves and excitation intensities of the real branch points in seismoelectric logs. It is found that the REP's phase, which reflects the phase discrepancy between the Stoneley-wave-induced electric field and the acoustic pressure, is sensitive to formation permeability. To check the relation between permeability and REP's phase qualitatively, an approximate expression of the tangent of the REP's argument is derived theoretically as tan(θEP) ≈-ωc/ω = -φη/ (2πfα ∞ρfκ0), where θEPdenotes the arguments of the REP and their principal value is the REP's phase,ω is the angular frequency,ωc is a critical angular frequency that separates the low-frequency viscous flow from the high-frequency inertial flow, φ is the porosity, α∞ is the tortuosity, κ0 is the Darcy permeability, ρf and η are the density and the viscosity of the pore

  11. Permeability of the San Andreas Fault Zone at Depth

    NASA Astrophysics Data System (ADS)

    Rathbun, A. P.; Song, I.; Saffer, D.

    2010-12-01

    Quantifying fault rock permeability is important toward understanding both the regional hydrologic behavior of fault zones, and poro-elastic processes that affect fault mechanics by mediating effective stress. These include long-term fault strength as well as dynamic processes that may occur during earthquake slip, including thermal pressurization and dilatancy hardening. Despite its importance, measurements of fault zone permeability for relevant natural materials are scarce, owing to the difficulty of coring through active fault zones seismogenic depths. Most existing measurements of fault zone permeability are from altered surface samples or from thinner, lower displacement faults than the SAF. Here, we report on permeability measurements conducted on gouge from the actively creeping Central Deformation Zone (CDZ) of the San Andreas Fault, sampled in the SAFOD borehole at a depth of ~2.7 km (Hole G, Run 4, sections 4,5). The matrix of the gouge in this interval is predominantly composed of particles <10 µm, with ~5 vol% clasts of serpentinite, very fine-grained sandstone, and siltstone. The 2.6 m-thick CDZ represents the main fault trace and hosts ~90% of the active slip on the SAF at this location, as documented by repeated casing deformation surveys. We measured permeability in two different configurations: (1) in a uniaxial pressure cell, in which a sample is placed into a rigid steel ring which imposes a zero lateral strain condition and subjected to axial load, and (2) in a standard triaxial system under isostatic stress conditions. In the uniaxial configuration, we obtained permeabilities at axial effective stresses up to 90 MPa, and in the triaxial system up to 10 MPa. All experiments were conducted on cylindrical subsamples of the SAFOD core 25 mm in diameter, with lengths ranging from 18mm to 40mm, oriented for flow approximately perpendicular to the fault. In uniaxial tests, permeability is determined by running constant rate of strain (CRS) tests up

  12. Permeability Modification Using a Reactive Alkaline-Soluble Biopolymer

    SciTech Connect

    Snadra L. Fox; X. Xie; K. D. Schaller; E. P. Robertson; G. A. Bala

    2003-10-01

    Polymer injection has been used in reservoirs to alleviate contrasting permeability zones. Current technology relies on the use of cross-linking agents to initiate gelation. The use of biological polymers are advantageous in that they can block high permeability areas, are environmentally friendly, and have potential to form reversible gels without the use of hazardous cross-linkers. Recent efforts at the Idaho National Engineering and Environmental Laboratory (INEEL) have produced a reactive alkaline-soluble biopolymer from Agrobacterium sp. ATCC no. 31749 that gels upon decreasing the pH of the polymeric solution. The focus of this study was to determine the impact an alkaline-soluble biopolymer can have on sandstone permeability. Permeability modification was investigated by injecting solubilized biopolymer into Berea sandstone cores and defining the contribution of pH, salt, temperature, and Schuricht crude oil on biopolymer gelation. The biopolymer was soluble in KOH at a pH greater than 11.4 and gelled when the pH dropped below 10.8. The Berea sandstone core buffered the biopolymer solution, decreasing the pH sufficiently to form a gel, which subsequently decreased the permeability. The effluent pH of the control cores injected with 0.01 {und M} KOH (pH 12.0) and 0.10{und M} KOH (pH 13.0) decreased to 10.6 and 12.7, respectively. The permeability of the sandstone core injected with biopolymer was decreased to greater than 95% of the original permeability at 25 C in the presence of 2% NaCl, and Schuricht crude oil; however, the permeability increased when the temperature of the core was increased to 60 C. Residual resistance factors as high as 792 were seen in Berea cores treated with biopolymer. The buffering capacity of sandstone has been demonstrated to reduce the pH of a biopolymer solution sufficiently to cause the polymer to form a stable in-situ gel. This finding could potentially lead to alternate technology for permeability modification, thus

  13. Experimental investigation of turbulent flow over a permeable rough wall

    NASA Astrophysics Data System (ADS)

    Kim, T.; Blois, G.; Best, J.; Christensen, K. T.

    2015-12-01

    Permeable walls are encountered in a variety of geophysical flows, including alluvial river beds, canopies and urban environments. Permeable walls possess very different boundary conditions as compared to classic impermeable walls (i.e. the slip condition and penetration of flow into the bed). Permeability allows flow interactions across the wall interface, resulting in notable mass, momentum and energy exchange. Such exchange takes place in the so-called transition layer and often occurs through turbulent flow mechanisms. It is increasingly recognized that turbulence plays a key role in a number of important natural functions, including biogeochemical as well as geomorphological processes. However, the flow physics of the transition layer are still poorly understood due to a lack of quantitative investigation of these permeable systems within which physical and optical access are severely compromised. This is particularly true for state-of-the-art flow measurement techniques such as particle image velocimetry (PIV) that require unaberrated optical access to the measurement locations. To overcome optical limitations, a refractive index matching (RIM) technique was employed herein to gain full optical access to the transition layer. Sodium Iodide aqueous solution (63% by weight and RI ~ 1.496 at 20°C) served as a working fluid, and an acrylic resin (RI ~ 1.499) was chosen for fabricating wall models. Measurements were performed using high-resolution planar PIV in different configurations to characterize the turbulent boundary layer and the transition layer. The wall models comprised uniform spheres packed in a cubic arrangement, and two cases were modeled - impermeable and permeable walls that were both rough. To eliminate the effect of roughness, and thus isolate the effect of permeability, the surface roughness of the two wall models was kept identical. This allowed us to obtain a more meaningful comparison and highlight the impact of wall permeability in natural

  14. Acetazolamide inhibits osmotic water permeability by interaction with aquaporin-1.

    PubMed

    Gao, Junwei; Wang, Xiaohua; Chang, Yongjie; Zhang, Jianzhao; Song, Qianliu; Yu, Heming; Li, Xuejun

    2006-03-15

    Water channel proteins, known as aquaporins, are transmembrane proteins that mediate osmotic water permeability. In a previous study, we found that acetazolamide could inhibit osmotic water transportation across Xenopus oocytes by blocking the function of aquaporin-1 (AQP1). The purpose of the current study was to confirm the effect of acetazolamide on water osmotic permeability using the human embryonic kidney 293 (HEK293) cells transfected with pEGFP/AQP1 and to investigate the interaction between acetazolamide and AQP1. The fluorescence intensity of HEK293 cells transfected with pEGFP/AQP1, which corresponds to the cell volume when the cells swell in a hyposmotic solution, was recorded under confocal laser fluorescence microscopy. The osmotic water permeability was assessed by the change in the ratio of cell fluorescence to certain cell area. Acetazolamide, at concentrations of 1 and 10muM, inhibited the osmotic water permeability in HEK293 cells transfected with pEGFP/AQP1. The direct binding between acetazolamide and AQP1 was detected by surface plasmon resonance. AQP1 was prepared from rat red blood cells and immobilized on a CM5 chip. The binding assay showed that acetazolamide could directly interact with AQP1. This study demonstrated that acetazolamide inhibited osmotic water permeability through interaction with AQP1. PMID:16480680

  15. Genetic aspects of intestinal permeability in inflammatory bowel disease.

    PubMed

    Takeuchi, Ken; Maiden, Laurence; Bjarnason, Ingvar

    2004-01-01

    There is a long-standing belief that disruption of the intestinal barrier function may lead to systemic and local intestinal disease. The role of increased intestinal permeability in Crohn's disease is reviewed here. What is not in doubt is that intestinal permeability in patients with Crohn's disease is increased proportional to disease activity; it can be used to predict clinical relapse of disease and prognosis; and a small proportion of first-degree relatives have increased intestinal permeability. This last finding has been subject to much speculation. In particular it has been suggested that it represents a genetically determined abnormality. If so it might play an important pathogenic process in the disease. However this permeability change in relatives does not conform to a classical inheritance pattern and in some studies it is found in the patients' spouses. This suggests an environmental cause for the changes. However proponents of an environmental factor have been singularly inactive in attempting to identify this agent(s). In view of recent research it seems likely that the increased intestinal permeability in relatives of Crohn's patients may be secondary to sub-clinical intestinal inflammation. This inflammation conforms to an inherited additive trait. The genetic basis for this inflammation is being studied.

  16. Simulating bioclogging effects on dynamic riverbed permeability and infiltration

    NASA Astrophysics Data System (ADS)

    Newcomer, Michelle E.; Hubbard, Susan S.; Fleckenstein, Jan H.; Maier, Ulrich; Schmidt, Christian; Thullner, Martin; Ulrich, Craig; Flipo, Nicolas; Rubin, Yoram

    2016-04-01

    Bioclogging in rivers can detrimentally impact aquifer recharge. This is particularly so in dry regions, where losing rivers are common, and where disconnection between surface water and groundwater (leading to the development of an unsaturated zone) can occur. Reduction in riverbed permeability due to biomass growth is a time-variable parameter that is often neglected, yet permeability reduction from bioclogging can introduce order of magnitude changes in seepage fluxes from rivers over short (i.e., monthly) timescales. To address the combined effects of bioclogging and disconnection on infiltration, we developed numerical representations of bioclogging processes within a one-dimensional, variably saturated flow model representing losing-connected and losing-disconnected rivers. We tested these formulations using a synthetic case study informed with biological data obtained from the Russian River, California, USA. Our findings show that modeled biomass growth reduced seepage for losing-connected and losing-disconnected rivers. However, for rivers undergoing disconnection, infiltration declines occurred only after the system was fully disconnected. Before full disconnection, biologically induced permeability declines were not significant enough to offset the infiltration gains introduced by disconnection. The two effects combine to lead to a characteristic infiltration curve where peak infiltration magnitude and timing is controlled by permeability declines relative to hydraulic gradient gains. Biomass growth was found to hasten the onset of full disconnection; a condition we term `effective disconnection'. Our results show that river infiltration can respond dynamically to bioclogging and subsequent permeability declines that are highly dependent on river connection status.

  17. Influence of overconsolidated condition on permeability evolution in silica sand

    NASA Astrophysics Data System (ADS)

    Kimura, S.; Kaneko, H.; Ito, T.; Nishimura, O.; Minagawa, H.

    2013-12-01

    Permeability of sediments is important factors for production of natural gas from natural gas hydrate bearing layers. Methane-hydrate is regarded as one of the potential resources of natural gas. As results of coring and logging, the existence of a large amount of methane-hydrate is estimated in the Nankai Trough, offshore central Japan, where many folds and faults have been observed. In the present study, we investigate the permeability of silica sand specimen forming the artificial fault zone after large displacement shear in the ring-shear test under two different normal consolidated and overconsolidated conditions. The significant influence of overconsolidation ratio (OCR) on permeability evolution is not found. The permeability reduction is influenced a great deal by the magnitude of normal stress during large displacement shearing. The grain size distribution and structure observation in the shear zone of specimen after shearing at each normal stress level are analyzed by laser scattering type particle analyzer and scanning electron microscope, respectively. It is indicated that the grain size and porosity reduction due to the particle crushing are the factor of the permeability reduction. This study is financially supported by METI and Research Consortium for Methane Hydrate Resources in Japan (the MH21 Research Consortium).

  18. Determination of hydrogen permeability in commercial and modified superalloys

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, S.; Peterman, W.

    1983-01-01

    The results of hydrogen permeability measurements on several iron- and cobalt-base alloys as well as on two long-ranged ordered alloys over the range of 705 to 870 C (1300 to 1600 F) are summarized. The test alloys included wrought alloys N-155, IN 800, A-286, 19-9DL, and 19-9DL modifications with aluminum, niobium, and misch metal. In addition, XF-818, CRM-6D, SA-F11, and HS-31 were evaluated. Two wrought long-range ordered alloys, Ni3Al and (Fe,Ni)3(V,Al) were also evaluated. All tests were conducted at 20.7 MPa pressure in either pure and/or 1% CO2-doped H2 for test periods as long as 133 h. Detailed analyses were conducted to determine the relative permeability rankings of these alloys and the effect of doping, exit surface oxidation, specimen design variations, and test duration on permeability coefficient, and permeation activation energies were determined. The two long-range ordered alloys had the lowest permeability coefficients in pure H2 when compared with the eight commercial alloys and their modifications. With CO2 doping, significant decrease in permeability was observed in commercial alloys--no doped tests were conducted with the long-range ordered alloys.

  19. Genetic aspects of intestinal permeability in inflammatory bowel disease.

    PubMed

    Takeuchi, Ken; Maiden, Laurence; Bjarnason, Ingvar

    2004-01-01

    There is a long-standing belief that disruption of the intestinal barrier function may lead to systemic and local intestinal disease. The role of increased intestinal permeability in Crohn's disease is reviewed here. What is not in doubt is that intestinal permeability in patients with Crohn's disease is increased proportional to disease activity; it can be used to predict clinical relapse of disease and prognosis; and a small proportion of first-degree relatives have increased intestinal permeability. This last finding has been subject to much speculation. In particular it has been suggested that it represents a genetically determined abnormality. If so it might play an important pathogenic process in the disease. However this permeability change in relatives does not conform to a classical inheritance pattern and in some studies it is found in the patients' spouses. This suggests an environmental cause for the changes. However proponents of an environmental factor have been singularly inactive in attempting to identify this agent(s). In view of recent research it seems likely that the increased intestinal permeability in relatives of Crohn's patients may be secondary to sub-clinical intestinal inflammation. This inflammation conforms to an inherited additive trait. The genetic basis for this inflammation is being studied. PMID:15669640

  20. Direct Optofluidic Measurement of the Lipid Permeability of Fluoroquinolones.

    PubMed

    Cama, Jehangir; Schaich, Michael; Al Nahas, Kareem; Hernández-Ainsa, Silvia; Pagliara, Stefano; Keyser, Ulrich F

    2016-01-01

    Quantifying drug permeability across lipid membranes is crucial for drug development. In addition, reduced membrane permeability is a leading cause of antibiotic resistance in bacteria, and hence there is a need for new technologies that can quantify antibiotic transport across biological membranes. We recently developed an optofluidic assay that directly determines the permeability coefficient of autofluorescent drug molecules across lipid membranes. Using ultraviolet fluorescence microscopy, we directly track drug accumulation in giant lipid vesicles as they traverse a microfluidic device while exposed to the drug. Importantly, our measurement does not require the knowledge of the octanol partition coefficient of the drug - we directly determine the permeability coefficient for the specific drug-lipid system. In this work, we report measurements on a range of fluoroquinolone antibiotics and find that their pH dependent lipid permeability can span over two orders of magnitude. We describe various technical improvements for our assay, and provide a new graphical user interface for data analysis to make the technology easier to use for the wider community.

  1. Modulation of cerebral microvascular permeability by endothelial nicotinic acetylcholine receptors.

    PubMed

    Hawkins, Brian T; Egleton, Richard D; Davis, Thomas P

    2005-07-01

    Nicotine increases the permeability of the blood-brain barrier in vivo. This implies a possible role for nicotinic acetylcholine receptors in the regulation of cerebral microvascular permeability. Expression of nicotinic acetylcholine receptor subunits in cerebral microvessels was investigated with immunofluorescence microscopy. Positive immunoreactivity was found for receptor subunits alpha3, alpha5, alpha7, and beta2, but not subunits alpha4, beta3, or beta4. Blood-brain barrier permeability was assessed via in situ brain perfusion with [14C]sucrose. Nicotine increased the rate of sucrose entry into the brain from 0.3 +/- 0.1 to 1.1 +/- 0.2 microl.g(-1).min(-1), as previously described. This nicotine-induced increase in blood-brain barrier permeability was significantly attenuated by both the blood-brain barrier-permeant nicotinic antagonist mecamylamine and the blood-brain barrier-impermeant nicotinic antagonist hexamethonium to 0.5 +/- 0.2 and 0.3 +/- 0.2 microl.g(-1).min(-1), respectively. These data suggest that nicotinic acetylcholine receptors expressed on the cerebral microvascular endothelium mediate nicotine-induced changes in blood-brain barrier permeability.

  2. Time effect on shear strength and permeability of fly ash

    SciTech Connect

    Porbaha, A.; Pradhan, T.B.S.; Yamane, N.

    2000-04-01

    This paper investigates the effect of time on the shear strength and the permeability of fly ash, a major solid by-product of thermoelectric power plants. Direct shear tests using Mikasa's apparatus, conventional permeability tests, and consolidation tests were conducted on two silt-size fly ashes, with low free lime contents, obtained from two different power plants. The results show that the immediate settling of both fly ashes takes place in a short period of time during consolidation and does not change with time. The rate of increase in shear strength with time is different depending on the pozzolanic reactions taking place for the two ashes. The permeability tests under constant stresses of 49 and 98 kPa for 12 days show that the coefficient of permeability for the tested ashes is between 10{sup {minus}6} and 10{sup {minus}7} m/s. During this period the coefficient of permeability either remains constant (for the case of the ash with a lower free lime content) or is slightly reduced (for the ash with a higher free lime content). The practical implications and the limitations of using low lime silt-size fly ash in vertical drains in the stabilization of soft ground are also discussed.

  3. The evaluation of rock permeability with streaming current measurements

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Hu, Hengshan; Guan, Wei

    2016-09-01

    Rock permeability is an important parameter for the formation evaluation. In this paper, a new method with streaming current is proposed to determine the sample permeability based on the electrokinetic effects, and is proved by the experimental measurements. Corresponding to this method, we have designed an experimental setup and a test system, then performed the streaming current (potential) and electro-osmosis pressure experiments with 23 sandstone samples at 0.05 mol l-1 NaCl solution. The streaming current (potential) coefficient and electro-osmosis pressure coefficient are obtained, respectively, with the experimental data at low frequencies with AC lock-in technique. The electrokinetic permeabilities are further calculated with these coefficients. The results are consistent well with the gas permeability measured with Darcy's law, which verifies the current method for estimating rock permeability. Our measurements are also analysed and compared with previous measurements. The results indicate that our method can reflect the essence of electrokinetic effects better and simplify the electrokinetic measurements as well. In addition, we discuss the influences of experimental artefacts (core holder and confining pressure installation) on the electrokinetic data. The results show that the trough phenomenon, appeared in frequency curves of streaming current (potential) coefficients, is induced by the resonance of the core-holder/vibrator system. This is important for the design of electrokinetic setup and the analysis of low-frequency response of the electrokinetic coupling coefficients.

  4. Similarity & Instability in Flows Over Permeable Layers (Invited)

    NASA Astrophysics Data System (ADS)

    Ghisalberti, M.

    2013-12-01

    Permeable obstructions (such as seagrass meadows) are prevalent in the benthic region of freshwater and coastal environments. Their impact on the near-bed flow, turbulence and vertical transport is profound. Here, I use particle imaging and point velocity measurements in both steady and oscillatory flows to demonstrate three salient features of environmental flows over permeable layers: (1) A framework developed for vegetation canopies has the capacity to predict flow, turbulence and mixing properties over a wide range of permeable layers (from sediment beds to coral reefs to 'urban' canopies to ancient rangeomorph communities). (2) Steady flows are characterized by the development of a Kelvin-Helmholtz-type instability at the interface between the permeable layer and the free flow. These coherent structures dominate vertical mixing at the interface and generate regular oscillations in flow and transport. The height of the permeable layer relative to its drag length scale defines three regimes of obstructed shear flow. (3) Such instability is also observed in oscillatory flow when both the Reynolds and Keulegan-Carpenter numbers exceed threshold values. This is important in the prediction of residence time in ecologically-significant benthic habitats that exist in shallow (and therefore, typically, wave-dominated) coastal regions.

  5. High Temperature Permeability of Carbon Cloth Phenolic Composite

    NASA Technical Reports Server (NTRS)

    Park, O. Y.; Lawrence, T. W.

    2003-01-01

    The carbon fiber phenolic resin composite material used for the RSRM nozzle insulator occasionally experiences problems during operation from pocketing or spalling-like erosion and lifting of plies into the char layer. This phenomenon can be better understood if the permeability of the material at elevated temperatures is well defined. This paper describes an experimental approach to determining high temperature permeability of the carbon phenolic material used as the RSRM nozzle liner material. Two different approaches were conducted independently using disk and bar type specimens with the designed permeability apparatus. The principle of the apparatus was to subject a test specimen to a high pressure differential and a heat supply and to monitor both the pressure and temperature variations resulting from gas penetration through the permeable wall between the two chambers. The bar types, especially designed to eliminate sealing difficulties at a high temperature environment, were directly exposed to real time temperature elevation from 22 C to 260 C during the test period. The disk types were pre-heat treated up to 300 C for 8 hours and cooled to room temperature before testing. Nonlinear variation of downstream pressure at a certain temperature range implied moisture release and matrix pyrolysis. Permeability was calculated using a semi-numerical model of quasi-steady state. The test results and the numerical model are discussed in the paper.

  6. Direct Optofluidic Measurement of the Lipid Permeability of Fluoroquinolones

    PubMed Central

    Cama, Jehangir; Schaich, Michael; Al Nahas, Kareem; Hernández-Ainsa, Silvia; Pagliara, Stefano; Keyser, Ulrich F.

    2016-01-01

    Quantifying drug permeability across lipid membranes is crucial for drug development. In addition, reduced membrane permeability is a leading cause of antibiotic resistance in bacteria, and hence there is a need for new technologies that can quantify antibiotic transport across biological membranes. We recently developed an optofluidic assay that directly determines the permeability coefficient of autofluorescent drug molecules across lipid membranes. Using ultraviolet fluorescence microscopy, we directly track drug accumulation in giant lipid vesicles as they traverse a microfluidic device while exposed to the drug. Importantly, our measurement does not require the knowledge of the octanol partition coefficient of the drug – we directly determine the permeability coefficient for the specific drug-lipid system. In this work, we report measurements on a range of fluoroquinolone antibiotics and find that their pH dependent lipid permeability can span over two orders of magnitude. We describe various technical improvements for our assay, and provide a new graphical user interface for data analysis to make the technology easier to use for the wider community. PMID:27604156

  7. Controlling ferrofluid permeability across the blood-brain barrier model

    NASA Astrophysics Data System (ADS)

    Shi, Di; Sun, Linlin; Mi, Gujie; Sheikh, Lubna; Bhattacharya, Soumya; Nayar, Suprabha; Webster, Thomas J.

    2014-02-01

    In the present study, an in vitro blood-brain barrier model was developed using murine brain endothelioma cells (b.End3 cells). Confirmation of the blood-brain barrier model was completed by examining the permeability of FITC-Dextran at increasing exposure times up to 96 h in serum-free medium and comparing such values with values from the literature. After such confirmation, the permeability of five novel ferrofluid (FF) nanoparticle samples, GGB (ferrofluids synthesized using glycine, glutamic acid and BSA), GGC (glycine, glutamic acid and collagen), GGP (glycine, glutamic acid and PVA), BPC (BSA, PEG and collagen) and CPB (collagen, PVA and BSA), was determined using this blood-brain barrier model. All of the five FF samples were characterized by zeta potential to determine their charge as well as TEM and dynamic light scattering for determining their hydrodynamic diameter. Results showed that FF coated with collagen passed more easily through the blood-brain barrier than FF coated with glycine and glutamic acid based on an increase of 4.5% in permeability. Through such experiments, diverse magnetic nanomaterials (such as FF) were identified for: (1) MRI use since they were less permeable to penetrate the blood-brain barrier to avoid neural tissue toxicity (e.g. GGB) or (2) brain drug delivery since they were more permeable to the blood-brain barrier (e.g. CPB).

  8. Controlling ferrofluid permeability across the blood–brain barrier model.

    PubMed

    Shi, Di; Sun, Linlin; Mi, Gujie; Sheikh, Lubna; Bhattacharya, Soumya; Nayar, Suprabha; Webster, Thomas J

    2014-02-21

    In the present study, an in vitro blood–brain barrier model was developed using murine brain endothelioma cells (b.End3 cells). Confirmation of the blood–brain barrier model was completed by examining the permeability of FITCDextran at increasing exposure times up to 96 h in serum-free medium and comparing such values with values from the literature. After such confirmation, the permeability of five novel ferrofluid (FF) nanoparticle samples, GGB (ferrofluids synthesized using glycine, glutamic acid and BSA), GGC (glycine, glutamic acid and collagen), GGP (glycine, glutamic acid and PVA), BPC (BSA, PEG and collagen) and CPB (collagen, PVA and BSA), was determined using this blood–brain barrier model. All of the five FF samples were characterized by zeta potential to determine their charge as well as TEM and dynamic light scattering for determining their hydrodynamic diameter. Results showed that FF coated with collagen passed more easily through the blood–brain barrier than FF coated with glycine and glutamic acid based on an increase of 4.5% in permeability. Through such experiments, diverse magnetic nanomaterials (such as FF) were identified for: (1) MRI use since they were less permeable to penetrate the blood–brain barrier to avoid neural tissue toxicity (e.g. GGB) or (2) brain drug delivery since they were more permeable to the blood–brain barrier (e.g. CPB). PMID:24457539

  9. Direct Optofluidic Measurement of the Lipid Permeability of Fluoroquinolones.

    PubMed

    Cama, Jehangir; Schaich, Michael; Al Nahas, Kareem; Hernández-Ainsa, Silvia; Pagliara, Stefano; Keyser, Ulrich F

    2016-01-01

    Quantifying drug permeability across lipid membranes is crucial for drug development. In addition, reduced membrane permeability is a leading cause of antibiotic resistance in bacteria, and hence there is a need for new technologies that can quantify antibiotic transport across biological membranes. We recently developed an optofluidic assay that directly determines the permeability coefficient of autofluorescent drug molecules across lipid membranes. Using ultraviolet fluorescence microscopy, we directly track drug accumulation in giant lipid vesicles as they traverse a microfluidic device while exposed to the drug. Importantly, our measurement does not require the knowledge of the octanol partition coefficient of the drug - we directly determine the permeability coefficient for the specific drug-lipid system. In this work, we report measurements on a range of fluoroquinolone antibiotics and find that their pH dependent lipid permeability can span over two orders of magnitude. We describe various technical improvements for our assay, and provide a new graphical user interface for data analysis to make the technology easier to use for the wider community. PMID:27604156

  10. The effects of Bordetella pertussis vaccine on cerebral vascular permeability.

    PubMed

    Amiel, S A

    1976-12-01

    The effect of Bordetella pertussis vaccine on the cerebral vascular permeability in the mouse was studied by a radio-isotope method (131I-labelled HSA). Intravenous injection of 4 x 1010 heat-killed pertussis organisms caused a measurable increase in permeability in normal mice. Cryoinjury to the cerebral hemispheres resulted in a striking increase in vascular permeability at 24 h. This declined within 48 h and stabilized at a level fractionally higher than normal at 7 days ("healed lesion"). When pertussis organisms were injected into mice bearing ("healed lesion"). When pertussis organisms were injected into mice bearing "healed lesions" the increase in permeability was similar in magnitude to that in uninjured brain. The effect was increased by a second administration of pertussis 24 h after the first. The action of pertussis on a newly inflicted cryoinjury was protective. It is suggested that permeability changes in the cerebral vessels may be involved in the evolution of the encephalopathy attributed to the use of Bordetella pertussis vaccine in man.

  11. Calculation of the effective permeability of saturated random porous media

    NASA Astrophysics Data System (ADS)

    Ostvar, S.; Wood, B. D.; Apte, S.; Liburdy, J.

    2014-12-01

    Estimation of the effective permeability tensor is an essential part of Darcy-scale representations of flow in porous media. The permeability tensor itself is a property of the medium, and depends only on the microscale geometry of the system. Determining the functional relationships between effective permeability (or conductivity in the general sense) and the structure of the medium is an old problem, with the earliest results for ordered porous media dating the 1920's. In this presentation, we report on the results of (1) detailed theory development, and (2) computations for the effective permeability tensor in fully-saturated random sphere packs, with a focus on the computational results. The theory is developed by volume averaging the Stokes equations, and using developing appropriate closures via potential theory, and has been reported on previously. For the computations, we have adopted an immersed boundary method to fully resolve the pore-scale velocity field. From our results, we compute the hydraulic permeability for both ordered and random media, and we compare these results with existing analytical solutions for the hydraulic conductivity in periodic arrays.

  12. A mechanistic model for permeability evolution in fractured sorbing media

    NASA Astrophysics Data System (ADS)

    Wang, Shugang; Elsworth, Derek; Liu, Jishan

    2012-06-01

    A mechanistic model is presented to represent the evolution of permeability in fractured sorbing media such as coal beds and organic-rich shales. This model accommodates key competing processes of poromechanical dilation and sorption-induced swelling. We show that the significant difference in stiffness between fracture and matrix transforms the composite system from globally unconstrained to locally constrained by the development of a virtual "stiff shell" that envelops the perimeter of a representative elementary volume containing a fracture. It is this transformation that results in swelling-induced permeability reduction at low (sorbing) gas pressures and self consistently allows competitive dilation of the fracture as gas pressures are increased. Importantly, net dilation is shown to require a mismatch in the Biot coefficients of fracture and matrix with the coefficient for the fracture exceeding that for the matrix—a condition that is logically met. Permeability evolution is cast in terms of series and parallel models with the series model better replicating observational data. The model may be cast in terms of nondimensional parameters representing sorptive and poromechanical effects and modulated by the sensitivity of the fracture network to dilation or compaction of the individual fractures. This latter parameter encapsulates the effects of fracture spacing and initial permeability and scale changes in permeability driven by either sorption or poromechanical effects. This model is applied to well-controlled observational data for different ranks of coals and different gases (He, CO2) and satisfactory agreement is obtained.

  13. The evaluation of rock permeability with streaming current measurements

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Hu, Hengshan; Guan, Wei

    2016-06-01

    Rock permeability is an important parameter for the formation evaluation. In this paper, a new method with streaming current is proposed to determine the sample permeability based on the electrokinetic effects, and is proved by the experimental measurements. Corresponding to this method, we have designed an experimental setup and a test system, then performed the streaming current (potential) and electroosmosis pressure experiments with 23 sandstone samples at 0.05 mol/l NaCl solution. The streaming current (potential) coefficient and electroosmosis pressure coefficient are obtained respectively with the experimental data at low frequencies with AC lock-in technique. The electrokinetic permeabilities are further calculated with these coefficients. The results are consistent well with the gas permeability measured with Darcy's law, which verifies the current method for estimating rock permeability. Our measurements are also analyzed and compared with previous measurements. The results indicate that our method can reflect the essence of electrokinetic effects better and simplify the electrokinetic measurements as well. In addition, we discuss the influences of experimental artefacts (core-holder and confining pressure installation) on the electrokinetic data. The results show that the trough phenomenon, appeared in frequency curves of streaming current (potential) coefficients, is induced by the resonance of the core-holder/vibrator system. This is important for the design of electrokinetic setup and the analysis of low frequency response of the electrokinetic coupling coefficients.

  14. Tubedown regulation of retinal endothelial permeability signaling pathways

    PubMed Central

    Ho, Nhu; Gendron, Robert L.; Grozinger, Kindra; Whelan, Maria A.; Hicks, Emily Anne; Tennakoon, Bimal; Gardiner, Danielle; Good, William V.; Paradis, Hélène

    2015-01-01

    ABSTRACT Tubedown (Tbdn; Naa15), a subunit of the N-terminal acetyltransferase NatA, complexes with the c-Src substrate Cortactin and supports adult retinal homeostasis through regulation of vascular permeability. Here we investigate the role of Tbdn expression on signaling components of retinal endothelial permeability to understand how Tbdn regulates the vasculature and supports retinal homeostasis. Tbdn knockdown-induced hyperpermeability to Albumin in retinal endothelial cells was associated with an increase in the levels of activation of the Src family kinases (SFK) c-Src, Fyn and Lyn and phospho-Cortactin (Tyr421). The knockdown of Cortactin expression reduced Tbdn knockdown-induced permeability to Albumin and the levels of activated SFK. Inhibition of SFK in retinal endothelial cells decreased Tbdn knockdown-induced permeability to Albumin and phospho-Cortactin (Tyr421) levels. Retinal lesions of endothelial-specific Tbdn knockdown mice, with tissue thickening, fibrovascular growth, and hyperpermeable vessels displayed an increase in the levels of activated c-Src. Moreover, the retinal lesions of patients with proliferative diabetic retinopathy (PDR) associated with a loss of Tbdn expression and hyperpermeability to Albumin displayed increased levels of activated SFK in retinal blood vessels. Taken together, these results implicate Tbdn as an important regulator of retinal endothelial permeability and homeostasis by modulating a signaling pathway involving c-Src and Cortactin. PMID:26142315

  15. Permeability of rock samples from Cajon Pass, California

    USGS Publications Warehouse

    Morrow, C.; Byerlee, J.

    1988-01-01

    Room temperature, steady-state flow measurements of permeability were conducted on 15 unfractured core samples collected at depths between 270 and 2100 m in the Cajon Pass drillhole. Confining and pore pressures were set to the lithostat and hydrostat for each depth. The first 500 m encountered in the drill hole is composed of sandstones with typically high permeabilities of around 10-17m2. The crystalline rocks between 500 and 2100 m show a systematic decrease in permeability with depth from 10-19 to less than 10-21m2. These values are particularly low relative to the applied effective stresses of only 10-30 MPa, and may be a result of the extensive crack healing that was observed in most samples. -Authors

  16. Flow and permeability structure of the Beowawe, Nevada hydrothermal system

    SciTech Connect

    Faulder, D.D.; Johnson, S.D.; Benoit, W.R.

    1997-05-01

    A review of past geologic, geochemical, hydrological, pressure transient, and reservoir engineering studies of Beowawe suggests a different picture of the reservoir than previously presented. The Beowawe hydrothermal contains buoyant thermal fluid dynamically balanced with overlying cold water, as shown by repeated temperature surveys and well test results. Thermal fluid upwells from the west of the currently developed reservoir at the intersection of the Malpais Fault and an older structural feature associated with mid-Miocene rifting. A tongue of thermal fluid rises to the east up the high permeability Malpais Fault, discharges at the Geysers area, and is in intimate contact with overlying cooler water. The permeability structure is closely related to the structural setting, with the permeability of the shallow hydrothermal system ranging from 500 to 1,000 D-ft, while the deeper system ranges from 200 to 400 D-ft.

  17. The mitochondrial permeability transition pore: a mystery solved?

    PubMed Central

    Bernardi, Paolo

    2013-01-01

    The permeability transition (PT) denotes an increase of the mitochondrial inner membrane permeability to solutes with molecular masses up to about 1500 Da. It is presumed to be mediated by opening of a channel, the permeability transition pore (PTP), whose molecular nature remains a mystery. Here I briefly review the history of the PTP, discuss existing models, and present our new results indicating that reconstituted dimers of the FOF1 ATP synthase form a channel with properties identical to those of the mitochondrial megachannel (MMC), the electrophysiological equivalent of the PTP. Open questions remain, but there is now promise that the PTP can be studied by genetic methods to solve the large number of outstanding problems. PMID:23675351

  18. Correlation between permeability and groundwater flow patterns in carbonate rocks

    NASA Astrophysics Data System (ADS)

    Park, Y.; Lee, J.; Park, Y.; Keehm, Y.

    2011-12-01

    Groundwater flow in carbonate rocks is controlled by many factors such as degree of fracture and pore development, weathering and diagenesis. Among these factors, fracture is main factor and can form main flow path. Also, flow patterns in carbonate area are decided by these factors. This study was performed to understand factors controlling permeability and flow patterns in carbonate area and to evaluate correlation between permeability and flow patterns. Data used in this study were collected from many literatures and these data were analyzed and evaluated using graphic and statistical analysis. In many carbonate areas, branching conduit patterns were dominant. Of these areas, permeability was relatively high in areas where moving distance of flow was short and hydraulic gradient was steep. This work was supported by the Energy Resources R&D program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy (No. 2009201030001A).

  19. Water retention and gas relative permeability of two industrial concretes

    SciTech Connect

    Chen Wei; Liu Jian; Brue, Flore; Skoczylas, Frederic; Davy, C.A.; Bourbon, Xavier; Talandier, Jean

    2012-07-15

    This experimental study aims at identifying the water retention properties of two industrial concretes to be used for long term underground nuclear waste storage structures. Together with water retention, gas transfer properties are identified at varying water saturation level, i.e. relative gas permeability is assessed directly as a function of water saturation level S{sub w}. The influence of the initial de-sorption path and of the subsequent re-saturation are analysed both in terms of water retention and gas transfer properties. Also, the influence of concrete microstructure upon water retention and relative gas permeability is assessed, using porosity measurements, analysis of the BET theory from water retention properties, and MIP. Finally, a single relative gas permeability curve is proposed for each concrete, based on Van Genuchten-Mualem's statistical model, to be used for continuous modelling approaches of concrete structures, both during drying and imbibition.

  20. System level permeability modeling of porous hydrogen storage materials.

    SciTech Connect

    Kanouff, Michael P.; Dedrick, Daniel E.; Voskuilen, Tyler

    2010-01-01

    A permeability model for hydrogen transport in a porous material is successfully applied to both laboratory-scale and vehicle-scale sodium alanate hydrogen storage systems. The use of a Knudsen number dependent relationship for permeability of the material in conjunction with a constant area fraction channeling model is shown to accurately predict hydrogen flow through the reactors. Generally applicable model parameters were obtained by numerically fitting experimental measurements from reactors of different sizes and aspect ratios. The degree of channeling was experimentally determined from the measurements and found to be 2.08% of total cross-sectional area. Use of this constant area channeling model and the Knudsen dependent Young & Todd permeability model allows for accurate prediction of the hydrogen uptake performance of full-scale sodium alanate and similar metal hydride systems.

  1. Groundwater protection from cadmium contamination by permeable reactive barriers.

    PubMed

    Di Natale, F; Di Natale, M; Greco, R; Lancia, A; Laudante, C; Musmarra, D

    2008-12-30

    This work studies the reliability of an activated carbon permeable reactive barrier in removing cadmium from a contaminated shallow aquifer. Laboratory tests have been performed to characterize the equilibrium and kinetic adsorption properties of the activated carbon in cadmium-containing aqueous solutions. A 2D numerical model has been used to describe pollutant transport within a groundwater and the pollutant adsorption on the permeable adsorbing barrier (PRB). In particular, it has been considered the case of a permeable adsorbing barrier (PAB) used to protect a river from a Cd(II) contaminated groundwater. Numerical results show that the PAB can achieve a long-term efficiency by preventing river pollution for several months.

  2. Apparatus for providing directional permeability measurements in subterranean earth formations

    DOEpatents

    Shuck, Lowell Z.

    1977-01-01

    Directional permeability measurements are provided in a subterranean earth formation by injecting a high-pressure gas from a wellbore into the earth formation in various azimuthal directions with the direction having the largest pressure drop being indicative of the maximum permeability direction. These measurements are provided by employing an inflatable boot containing a plurality of conduits in registry with a like plurality of apertures penetrating the housing at circumferentially spaced-apart locations. These conduits are, in turn, coupled through a valved manifold to a source of pressurized gas so that the high-pressure gas may be selectively directed through any conduit into the earth formation defining the bore with the resulting difference in the pressure drop through the various conduits providing the permeability measurements.

  3. Benthic exchange and biogeochemical cycling in permeable sediments.

    PubMed

    Huettel, Markus; Berg, Peter; Kostka, Joel E

    2014-01-01

    The sandy sediments that blanket the inner shelf are situated in a zone where nutrient input from land and strong mixing produce maximum primary production and tight coupling between water column and sedimentary processes. The high permeability of the shelf sands renders them susceptible to pressure gradients generated by hydrodynamic and biological forces that modulate spatial and temporal patterns of water circulation through these sediments. The resulting dynamic three-dimensional patterns of particle and solute distribution generate a broad spectrum of biogeochemical reaction zones that facilitate effective decomposition of the pelagic and benthic primary production products. The intricate coupling between the water column and sediment makes it challenging to quantify the production and decomposition processes and the resultant fluxes in permeable shelf sands. Recent technical developments have led to insights into the high biogeochemical and biological activity of these permeable sediments and their role in the global cycles of matter.

  4. The Interfacial-Area-Based Relative Permeability Function

    SciTech Connect

    Zhang, Z. F.; Khaleel, Raziuddin

    2009-09-25

    CH2M Hill Plateau Remediation Company (CHPRC) requested the services of the Pacific Northwest National Laboratory (PNNL) to provide technical support for the Remediation Decision Support (RDS) activity within the Soil & Groundwater Remediation Project. A portion of the support provided in FY2009, was to extend the soil unsaturated hydraulic conductivity using an alternative approach. This alternative approach incorporates the Brooks and Corey (1964), van Genuchten (1980), and a modified van Genuchten water-retention models into the interfacial-area-based relative permeability model presented by Embid (1997). The general performance of the incorporated models is shown using typical hydraulic parameters. The relative permeability models for the wetting phase were further examined using data from literature. Results indicate that the interfacial-area-based model can describe the relative permeability of the wetting phase reasonably well.

  5. Lead induces increased water permeability in astrocytes expressing aquaporin 4.

    PubMed

    Gunnarson, E; Axehult, G; Baturina, G; Zelenin, S; Zelenina, M; Aperia, A

    2005-01-01

    The water channel aquaporin 4 (AQP4) is abundantly expressed in astrocytes. There is now compelling evidence that AQP4 may contribute to an unfavorable course in brain edema. Acute lead intoxication is a condition that causes brain damage preceded by brain edema. Here we report that lead increases AQP4 water permeability (P(f)) in astrocytes. A rat astrocyte cell line that does not express aquaporin 4 was transiently transfected with aquaporin 4 tagged with green fluorescent protein (GFP). Using confocal laser scanning microscopy we measured water permeability in these cells and in AQP4-negative cells located on the same plate. AQP4-expressing astrocytes had a three-fold higher water permeability than astrocytes not expressing AQP4. Lead exposure induced a significant, 40%, increase in water permeability in astrocytes expressing AQP4, but had no effect on P(f) in astrocytes not expressing AQP4. The increase in water permeability persisted after lead washout, while treatment with a lead chelator, meso-2,3-dimercaptosuccinic acid, abolished the lead-induced increase in P(f). The effect of lead was attenuated in the presence of a calcium (Ca(2+))/calmodulin-dependent protein kinase II (CaMKII) inhibitor, but not in the presence of a protein kinase C inhibitor. In cells expressing AQP4 where the consensus site for CaMKII phosphorylation was mutated, lead failed to increase water permeability. Lead exposure also increased P(f) in rat astroglial cells in primary culture, which express endogenous AQP4. Lead had no effect on P(f) in astrocytes transfected with aquaporin 3. In situ hybridization studies on rat brain after oral lead intake for three days showed no change in distribution of AQP4 mRNA. It is suggested that lead-triggered stimulation of water transport in AQP4-expressing astrocytes may contribute to the pathology of acute lead intoxication.

  6. Pore-structure models of hydraulic conductivity for permeable pavement

    NASA Astrophysics Data System (ADS)

    Kuang, X.; Sansalone, J.; Ying, G.; Ranieri, V.

    2011-03-01

    SummaryPermeable pavement functions as a porous infrastructure interface allowing the infiltration and evaporation of rainfall-runoff while functioning as a relatively smooth load-bearing surface for vehicular transport. Hydraulic conductivity ( k) of permeable pavement is an important hydraulic property and is a function of the pore structure. This study examines k for a cementitious permeable pavement (CPP) through a series of pore-structure models. Measurements utilized include hydraulic head as well as total porosity, ( ϕ t), effective porosity ( ϕ e), tortuosity ( L e/ L) and pore size distribution (PSD) indices generated through X-ray tomography (XRT). XRT results indicate that the permeable pavement pore matrix is hetero-disperse, with high tortuosity and ϕ t ≠ ϕ e. Power law models of k- ϕ t and k- ϕ e relationships are developed for a CPP mix design. Results indicate that the Krüger, Fair-Hatch, Hazen, Slichter, Beyer and Terzaghi models based on simple pore-structure indices do not reproduce measured k values. The conventional Kozeny-Carman model (KCM), a more parameterized pore-structure model, did not reproduce measured k values. This study proposes a modified KCM utilizing ϕ e, specific surface area (SSA) pe and weighted tortuosity ( L e/ L) w. Results demonstrate that such permeable pavement pore-structure parameters with the modified KCM can predict k. The k results are combined with continuous simulation modeling using historical rainfall to provide nomographs examining permeable pavement as a low impact development (LID) infrastructure component.

  7. Experimentally derived model to predict permeability behavior of mudstones

    NASA Astrophysics Data System (ADS)

    Schneider, J.; Flemings, P. B.; Day-Stirrat, R.; Germaine, J. T.

    2010-12-01

    We use uniaxial consolidation experiments to analyze the permeability evolution during consolidation for mudstones with varying composition to develop a predictive permeability model for mudstones. We admixed silt-sized silica to dry, natural Boston Blue Clay (BBC) powder in five different mass ratios. The result is mixtures of silty clay and clayey silt with percentages of clay-sized particles varying between 36 % and 57 %. To recreate natural conditions yet remove variability and soil disturbance, we resedimented all mixtures to a total stress of 100 kPa. We then loaded them to a vertical effective stress of 2.4 MPa in an uniaxial, constant-rate-of-strain consolidation device. We show that vertical permeability increases exponentially with void ratio and decreasing clay content. There is an order of magnitude difference in permeability at a given void ratio for clay contents varying from 36 % to 57 % (by mass). We developed a model that predicts the permeability of silt-clay mixtures based on knowledge of the composition and void ratio alone. The model assumes that flow occurs through the clay-matrix. Thus, the effective permeability is controlled by the void ratio of the clay fraction. At a given stress level, the clay void ratio increases with silt content: large pores are preserved in silty samples due to stress-bridging which does not allow the clay particles to consolidate. Mudstones are important to practical and fundamental programs. They are a key cap rock for subsurface hydrocarbons and geologic storage of CO2. Over the last decade, large amounts of natural gas have been produced from mudstone (shale) gas fields.

  8. Committee neural network model for rock permeability prediction

    NASA Astrophysics Data System (ADS)

    Bagheripour, Parisa

    2014-05-01

    Quantitative formulation between conventional well log data and rock permeability, undoubtedly the most critical parameter of hydrocarbon reservoir, could be a potent tool for solving problems associated with almost all tasks involved in petroleum engineering. The present study proposes a novel approach in charge of the quest for high-accuracy method of permeability prediction. At the first stage, overlapping of conventional well log data (inputs) was eliminated by means of principal component analysis (PCA). Subsequently, rock permeability was predicted from extracted PCs using multi-layer perceptron (MLP), radial basis function (RBF), and generalized regression neural network (GRNN). Eventually, a committee neural network (CNN) was constructed by virtue of genetic algorithm (GA) to enhance the precision of ultimate permeability prediction. The values of rock permeability, derived from the MPL, RBF, and GRNN models, were used as inputs of CNN. The proposed CNN combines results of different ANNs to reap beneficial advantages of all models and consequently producing more accurate estimations. The GA, embedded in the structure of the CNN assigns a weight factor to each ANN which shows relative involvement of each ANN in overall prediction of rock permeability from PCs of conventional well logs. The proposed methodology was applied in Kangan and Dalan Formations, which are the major carbonate reservoir rocks of South Pars Gas Field-Iran. A group of 350 data points was used to establish the CNN model, and a group of 245 data points was employed to assess the reliability of constructed CNN model. Results showed that the CNN method performed better than individual intelligent systems performing alone.

  9. Ocular Albumin Fluorophotometric Quantitation of Endotoxin-Induced Vascular Permeability

    PubMed Central

    Cousins, Scott W.; Rosenbaum, James T.; Guss, Robert B.; Egbert, Peter R.

    1982-01-01

    Bacterial endotoxin (lipopolysaccharide; LPS) is known to alter systemic vascular permeability, but this effect is difficult to monitor and quantitate in vivo. The ocular vessels of the rabbit are particularly sensitive to LPS. Using a slit lamp equipped with a fluorophotometer, we have adapted a method to quantitate endotoxin-induced ocular vascular permeability by measuring the accumulation of fluorescein isothiocyanate-conjugated albumin into the anterior chamber of the eye. After intravenous administration of Salmonella typhimurim LPS, the anterior chamber fluorescence and blood fluorescence were measured at intervals of 15 min and 1 h, respectively, over 4 h. In controls, maximal fluorescence in the anterior chamber was 3.1 ± 0.8% of blood fluorescence. Doses of LPS as low as 0.25 μg/kg produced an ocular/serum fluorescence ratio of 17.6 ± 4.9. A dose of 2.5 μg of LPS per kg tended to produce a higher ratio (68.0 ± 7.1) than a larger dose of 50 μg/kg (30.5 ± 16.6). Permeability changes began within 30 min after LPS, and the rate of dye accumulation varied over time, with maximal leakage usually occurring 90 min after LPS, but occasionally occurring much later. Repeated doses produced tolerance. By conjugating albumin to rhodamine and utilizing a second filter with the slit lamp to measure accumulation of this dye, we demonstrated the persistence of marked permeability during a period when intraocular fluorescein isothiocyanate and albumin levels were relatively constant. This methodology indicates that extremely low doses of LPS induce ocular permeability changes and that neither the time course nor the dose response of this effect is linear. Ocular fluorophotometry is a sensitive, noninvasive technique to study the dynamics and pharmacology of LPS-induced permeability changes. PMID:6806194

  10. In Vivo Measurement of Glioma-Induced Vascular Permeability

    PubMed Central

    Lee, Jisook; Baird, Andrew; Eliceiri, Brian P.

    2014-01-01

    The normal blood–brain barrier (BBB) consists of tight interendothelial cell junctions and adjacent astrocyte end feet separated by a basal lamina surrounding the endothelium. The interactions between the different cell types of BBB are disrupted in distinct patterns in the microenvironment of glioma. Malignant gliomas infiltrate the surrounding normal brain parenchyma; a process associated with vascular permeability (VP) and breakdown of the BBB. Herein, we describe methods to quantitatively measure glioma-induced vascular permeability, utilizing an orthotopic xenograft model of glioma. PMID:21874468

  11. Urban land use: Remote sensing of ground-basin permeability

    NASA Technical Reports Server (NTRS)

    Tinney, L. R.; Jensen, J. R.; Estes, J. E.

    1975-01-01

    A remote sensing analysis of the amount and type of permeable and impermeable surfaces overlying an urban recharge basin is discussed. An effective methodology for accurately generating this data as input to a safe yield study is detailed and compared to more conventional alternative approaches. The amount of area inventoried, approximately 10 sq. miles, should provide a reliable base against which automatic pattern recognition algorithms, currently under investigation for this task, can be evaluated. If successful, such approaches can significantly reduce the time and effort involved in obtaining permeability data, an important aspect of urban hydrology dynamics.

  12. LOW GRADIENT PERMEABILITY MEASUREMENTS IN A TRIAXIAL SYSTEM.

    USGS Publications Warehouse

    Olsen, H.W.; Nichols, R.W.; Rice, T.L.

    1985-01-01

    Permeability measurements were conducted with the flow-pump method on sand, sandy silt and silty clay specimens in a conventional triaxial system by introducing and withdrawing water at known constant flow rates into the base of a specimen with a flow-pump, and by monitoring the head difference induced across the length of the specimen with a sensitive differential pressure transducer. The results show that the previously reported advantages of the flow-pump method, compared with conventional constant head and falling head methods, were realized for permeability measurements in conventional triaxial equipment.

  13. [Investigation of membrane permeability of carp spermatozoa for water molecules].

    PubMed

    Pugovkin, A Iu; Kopeĭka, E F; Nardid, O A; Cherkashina, Ia O

    2014-01-01

    The fundamentals of a photometry method for determination of membrane permeability of some fish spermatozoa for water molecules are presented. Osmotic tolerance of carp spermatozoa membranes was studied using EPR-spectroscopy and photometric analysis methods. It was shown that carp spermatozoa look like the ideal osmometers in their reaction on media of different osmolarity. The value of membrane permeability of carp spermatozoa for water molecules was determined. Data obtained can be used in cryobiology for creating cryoprotective media and regimes of fish sperm cryopreservation. PMID:25715589

  14. Simulating residual saturation and relative permeability in heterogeneous formations

    SciTech Connect

    Paterson, L.; Painter, S.; Zhang, Xiaodong

    1996-12-31

    Network models are used to investigate the effect of correlated heterogeneity on capillary dominated displacements in porous media. Residual saturations and relative permeabilities are shown to be sensitive to the degree of correlation and anisotropy but not variability. The network models reproduce the experimental observation that relative permeability is greater in the direction parallel to the bedding compared to perpendicular to the bedding. The scatter commonly observed in core measurements of residual saturation is attributed to the presence of correlated heterogeneity in actual reservoir rocks.

  15. Diffusion of DNAPL Components into Low Permeability Soils

    NASA Astrophysics Data System (ADS)

    Ayral, D.; Demond, A. H.

    2013-12-01

    Hazardous waste sites contaminated with dense non-aqueous phase liquids (DNAPLs) have proven difficult to remediate. Even though DNAPLs may be removed from high permeability subsurface strata, the storage of compounds making up DNAPLs in low permeability strata constitutes a secondary source that contributes to a dissolved phase plume over an extended period of time. The movement of DNAPL constituents into and out of low permeable strata is considered to occur through diffusion. However, there are few experimentally measured effective diffusion coefficients for DNAPL components in low permeability soils. Thus, the effective diffusion coefficient is commonly estimated from the aqueous phase diffusion coefficient as a function of the porosity of the soil. This study presents measurements of effective diffusion coefficients of chlorinated solvents and an anionic surfactant dioctyl sodium sulfosuccinate (AOT) in silt and clay-silt mixtures. The experimental results are compared with estimated values to evaluate the performance of commonly used methods to estimate effective diffusion coefficients of DNAPL components. These estimation models generally suggest an increase in the effective diffusion coefficient with an increase in porosity. Yet, in low permeable soils with a substantial fraction of clay, the effective diffusion coefficient for chlorinated solutes decreases, although the porosity increases. Thus, calculations of the quantity of mass stored in low permeable strata may be in error if based on rates of diffusion calculated using such models. In addition to chlorinated solvents, DNAPLs often contain surfactants. The high molecular weight of these solutes results in problems when estimating their effective diffusion coefficient in low permeability soils, since commonly models were formulated for use with low molecular weight compounds. Furthermore, some clay minerals present in low permeable soils have a flexible structure which enables them to expand or

  16. Permeability and structure of resorcinol-formaldehyde gels

    SciTech Connect

    Scherer, G.W.; Alviso, C.; Pekala, R.; Gross, J.

    1996-12-31

    The permeability (D) of resorcinol-formaldehyde (RF) gels was measured using a beam-bending technique. For gels made at various solids contents and with different catalyst contents, the permeabilities ranged over a factor of {approximately} 50; the pore radii inferred from D varied from {approximately}3 to 30 nm. Pore radii obtained on RF aerogels using nitrogen desorption were severely affected by compression of the aerogel by capillary forces (resulting from the surface tension of liquid nitrogen). After correction for that effect, the desorption data were found to be in very good agreement with the pore sizes calculated from D.

  17. Pb2+ Modulates Ca2+ Membrane Permeability In Paramecium

    NASA Astrophysics Data System (ADS)

    Bernal-Martínez, Juan; Ortega Soto, Arturo

    2004-09-01

    Intracellular recording experiments in current clamp configuration were done to evaluate whether Pb2+ modulates ionic membrane permeability in the fresh water Paramecium tetraurelia. It was found that Pb2+ triggers in a dose-dependent manner, a burst of spontaneous action potentials followed by a robust and sustained after hyper-polarization. In addition, Pb2+ increased the frequency of firing the spontaneous Ca2+-Action Potential and also, the duration of Ca2+-Action Potential, in a dose and reversibly-dependent manner. These results suggest that Pb2+ increases calcium membrane permeability of Paramecium and probably activates a calcium-dependent-potassium conductance in the ciliate.

  18. Permeability in a state of partial solidification of aqueous solution

    NASA Astrophysics Data System (ADS)

    Okada, Masashi; Kang, Chaedong; Okiyama, Haruhiko

    A mushy region was formed by solidifying NaCl aqueous solution in a circular tube or a rectangular tube. The measurements of permeability were performed by changing volume fraction of liquid region in the mushy region. The dendritic ice in the solidification process was observed with a CCD microscope. The following results were obtained. The permeability increases with the volume fraction of liquid phase, and decreases with increasing the super-cooling degree of the solution or increasing the initial concentration of the solution, and is constant after the mushy region was formed. The arm space of dendrite becomes narrower as the super-cooling degree of the solution increases.

  19. Antidepressants Alter Cerebrovascular Permeability and Metabolic Rate in Primates

    NASA Astrophysics Data System (ADS)

    Preskorn, Sheldon H.; Raichle, Marcus E.; Hartman, Boyd K.

    1982-07-01

    External detection of the annihilation radiation produced by water labeled with oxygen-15 was used to measure cerebrovascular permeability and cerebral blood flow in six rhesus monkeys. Use of oxygen-15 also permitted assessment of cerebral metabolic rate in two of the monkeys. Amitriptyline produced a dose-dependent, reversible increase in permeability at plasma drug concentrations which are therapeutic for depressed patients. At the same concentrations the drug also produced a 20 to 30 percent reduction in cerebral metabolic rate. At higher doses normal autoregulation of cerebral blood flow was suspended, but responsivity to arterial carbon dioxide was normal.

  20. On cavity flow permeability testing of a sandstone.

    PubMed

    Selvadurai, P A; Selvadurai, A P S

    2007-01-01

    This paper describes a laboratory experiment designed to measure the bulk permeability of a cuboidal sample of sandstone measuring approximately 450 mm(2) in plan area and 508 mm in height. The relatively large dimensions of the sandstone specimen allow the determination of the permeability of the material by creating a central cavity that can be pressurized to maintain a constant flow rate. The paper describes the experimental details and the test procedure, and discusses the computational and analytic approaches that have been used to interpret the test results.

  1. Upscaling verticle permeability within a fluvio-aeolian reservoir

    SciTech Connect

    Thomas, S.D.; Corbett, P.W.M.; Jensen, J.L.

    1997-08-01

    Vertical permeability (k{sub v}) is a crucial factor in many reservoir engineering issues. To date there has been little work undertaken to understand the wide variation of k{sub v} values measured at different scales in the reservoir. This paper presents the results of a study in which we have modelled the results of a downhole well tester using a statistical model and high resolution permeability data. The work has demonstrates and quantifies a wide variation in k{sub v} at smaller, near wellbore scales and has implications for k{sub v} modelling at larger scales.

  2. Inflammatory mediators and modulation of blood-brain barrier permeability.

    PubMed

    Abbott, N J

    2000-04-01

    1. Unlike some interfaces between the blood and the nervous system (e.g., nerve perineurium), the brain endothelium forming the blood-brain barrier can be modulated by a range of inflammatory mediators. The mechanisms underlying this modulation are reviewed, and the implications for therapy of the brain discussed. 2. Methods for measuring blood-brain barrier permeability in situ include the use of radiolabeled tracers in parenchymal vessels and measurements of transendothelial resistance and rate of loss of fluorescent dye in single pial microvessels. In vitro studies on culture models provide details of the signal transduction mechanisms involved. 3. Routes for penetration of polar solutes across the brain endothelium include the paracellular tight junctional pathway (usually very tight) and vesicular mechanisms. Inflammatory mediators have been reported to influence both pathways, but the clearest evidence is for modulation of tight junctions. 4. In addition to the brain endothelium, cell types involved in inflammatory reactions include several closely associated cells including pericytes, astrocytes, smooth muscle, microglia, mast cells, and neurons. In situ it is often difficult to identify the site of action of a vasoactive agent. In vitro models of brain endothelium are experimentally simpler but may also lack important features generated in situ by cell:cell interaction (e.g. induction, signaling). 5. Many inflammatory agents increase both endothelial permeability and vessel diameter, together contributing to significant leak across the blood-brain barrier and cerebral edema. This review concentrates on changes in endothelial permeability by focusing on studies in which changes in vessel diameter are minimized. 6. Bradykinin (Bk) increases blood-brain barrier permeability by acting on B2 receptors. The downstream events reported include elevation of [Ca2+]i, activation of phospholipase A2, release of arachidonic acid, and production of free radicals, with

  3. Monitoring Strategies in Permeable Pavement Systems to Optimize Maintenance Scheduling

    EPA Science Inventory

    As the surface in a permeable pavement system clogs and performance decreases, maintenance is required to preserve the design function. Currently, guidance is limited for scheduling maintenance on an as needed basis. Previous research has shown that surface clogging in a permea...

  4. Two Relations to Estimate Membrane Permeability Using Milestoning.

    PubMed

    Votapka, Lane W; Lee, Christopher T; Amaro, Rommie E

    2016-08-25

    Prediction of passive permeation rates of solutes across lipid bilayers is important to drug design, toxicology, and other biological processes such as signaling. The inhomogeneous solubility-diffusion (ISD) equation is traditionally used to relate the position-dependent potential of mean force and diffusivity to the permeability coefficient. The ISD equation is derived via the Smoluchowski equation and assumes overdamped system dynamics. It has been suggested that the complex membrane environment may exhibit more complicated damping conditions. Here we derive a variant of the inhomogeneous solubility diffusion equation as a function of the mean first passage time (MFPT) and show how milestoning, a method that can estimate kinetic quantities of interest, can be used to estimate the MFPT of membrane crossing and, by extension, the permeability coefficient. We further describe a second scheme, agnostic to the damping condition, to estimate the permeability coefficient from milestoning results or other methods that compute a probability of membrane crossing. The derived relationships are tested using a one-dimensional Langevin dynamics toy system confirming that the presented theoretical methods can be used to estimate permeabilities given simulation and milestoning results. PMID:27154639

  5. Advanced Organic Permeable-Base Transistor with Superior Performance.

    PubMed

    Klinger, Markus P; Fischer, Axel; Kaschura, Felix; Scholz, Reinhard; Lüssem, Björn; Kheradmand-Boroujeni, Bahman; Ellinger, Frank; Kasemann, Daniel; Leo, Karl

    2015-12-16

    An optimized vertical organic permeable-base transistor (OPBT) competing with the best organic field-effect transistors in performance, while employing low-cost fabrication techniques, is presented. The OPBT stands out by its excellent power efficiency at the highest frequencies.

  6. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false High permeability hemodialysis system. 876.5860 Section 876.5860 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High...

  7. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false High permeability hemodialysis system. 876.5860 Section 876.5860 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High...

  8. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false High permeability hemodialysis system. 876.5860 Section 876.5860 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High...

  9. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false High permeability hemodialysis system. 876.5860 Section 876.5860 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High...

  10. Claudins and the Modulation of Tight Junction Permeability

    PubMed Central

    Günzel, Dorothee

    2013-01-01

    Claudins are tight junction membrane proteins that are expressed in epithelia and endothelia and form paracellular barriers and pores that determine tight junction permeability. This review summarizes our current knowledge of this large protein family and discusses recent advances in our understanding of their structure and physiological functions. PMID:23589827

  11. PERMEABLE TREATMENT WALL EFFECTIVENESS MONITORING PROJECT, NEVADA STEWART MINE

    EPA Science Inventory

    This report summarizes the results of Mine Waste Technology Program (MWTP) Activity III, Project 39, Permeable Treatment Wall Effectiveness Monitoring Project, implemented and funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by EPA and the U.S. De...

  12. The Edison Environmental Center Permeable Pavement Site - slides

    EPA Science Inventory

    This is a presentation for a second Community Outreach Event called "Chemistry Works!" at West Windsor Public Library on Saturday, November 5th. It will review the permeable pavement research project at the Edison Environmental center. Besides slide persentation, two demo units w...

  13. Quantifying tight-gas sandstone permeability via critical path analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rock permeability has been actively investigated over the past several decades by the geosciences community. However, its accurate estimation still presents significant technical challenges, especially in spatially complex rocks. In this letter, we apply critical path analysis (CPA) to estimate perm...

  14. Structure/permeability relationships of silicon-containing polyimides

    NASA Technical Reports Server (NTRS)

    Stern, S. A.; Vaidyanathan, R.; Pratt, J. R.

    1989-01-01

    The permeability to H2, O2, N2, CO2 and CH4 of three silicone-polyimide random copolymers and two polyimides containing silicon atoms in their backbone chains, was determined at 35.0 C and at pressures up to about 120 psig (approximately 8.2 atm). The copolymers contained different amounts of BPADA-m-PDA and amine-terminated poly (dimethyl siloxane) and also had different numbers of siloxane linkages in their silicone component. The polyimides containing silicon atoms (silicon-modified polyimides) were SiDA-4,4'-ODA and SiDA-p-PDA. The gas permeability and selectivity of the copolymers are more similar to those of their silicone component than of the polyimide component. By contrast, the permeability and selectivity of the silicon-modified polyimides are more similar to those of their parent polyimides, PMDA-4,4'-ODA and SiDA-p-PDA. The substitution of SiDA for the PMDA moiety in a polyimide appears to result in a significant increase in gas permeability, without a correspondingly large decrease in selectivity. The potential usefulness of the above polymers and copolymers as gas separation membranes is discussed.

  15. Iron abundance and magnetic permeability of the moon

    NASA Technical Reports Server (NTRS)

    Parkin, C. W.; Daily, W. D.; Dyal, P.

    1974-01-01

    A larger set of simultaneous data from the Apollo 12 lunar surface magnetometer and the Explorer 35 Ames magnetometer are used to construct a whole-moon hysteresis curve, from which a new value of global lunar permeability is determined to be mu = 1.012 + or - 0.006. The corresponding global induced dipole moment is 2.1 times ten to the eighteenth power gauss-cu cm for typical inducing fields of one ten-thousandth gauss in the lunar environment. From the permeability measurement, lunar free iron abundance is determined to be 2.5 + or - 2.0 wt %. Total iron abundance (sum of iron in the ferromagnetic and paramagnetic states) is calculated for two assumed compositional models of the lunar interior: a free iron/orthopyroxene lunar composition and a free iron/olivine composition. The overall lunar total iron abundance is determined to be 9.0 + or - 4.7 wt %. Other lunar models with a small iron core and with a shallow iron-rich layer are discussed in light of the measured global permeability. Effects on permeability and iron content calculations due to a possible lunar ionosphere are also considered.

  16. Dissolution-Driven Permeability Reduction of a Fractured Carbonate Caprock.

    PubMed

    Ellis, Brian R; Fitts, Jeffrey P; Bromhal, Grant S; McIntyre, Dustin L; Tappero, Ryan; Peters, Catherine A

    2013-04-01

    Geochemical reactions may alter the permeability of leakage pathways in caprocks, which serve a critical role in confining CO2 in geologic carbon sequestration. A caprock specimen from a carbonate formation in the Michigan sedimentary Basin was fractured and studied in a high-pressure core flow experiment. Inflowing brine was saturated with CO2 at 40°C and 10 MPa, resulting in an initial pH of 4.6, and had a calcite saturation index of -0.8. Fracture permeability decreased during the experiment, but subsequent analyses did not reveal calcite precipitation. Instead, experimental observations indicate that calcite dissolution along the fracture pathway led to mobilization of less soluble mineral particles that clogged the flow path. Analyses of core sections via electron microscopy, synchrotron-based X-ray diffraction imaging, and the first application of microbeam Ca K-edge X-ray absorption near edge structure, provided evidence that these occlusions were fragments from the host rock rather than secondary precipitates. X-ray computed tomography showed a significant loss of rock mass within preferential flow paths, suggesting that dissolution also removed critical asperities and caused mechanical closure of the fracture. The decrease in fracture permeability despite a net removal of material along the fracture pathway demonstrates a nonintuitive, inverse relationship between dissolution and permeability evolution in a fractured carbonate caprock. PMID:23633894

  17. Dissolution-Driven Permeability Reduction of a Fractured Carbonate Caprock.

    PubMed

    Ellis, Brian R; Fitts, Jeffrey P; Bromhal, Grant S; McIntyre, Dustin L; Tappero, Ryan; Peters, Catherine A

    2013-04-01

    Geochemical reactions may alter the permeability of leakage pathways in caprocks, which serve a critical role in confining CO2 in geologic carbon sequestration. A caprock specimen from a carbonate formation in the Michigan sedimentary Basin was fractured and studied in a high-pressure core flow experiment. Inflowing brine was saturated with CO2 at 40°C and 10 MPa, resulting in an initial pH of 4.6, and had a calcite saturation index of -0.8. Fracture permeability decreased during the experiment, but subsequent analyses did not reveal calcite precipitation. Instead, experimental observations indicate that calcite dissolution along the fracture pathway led to mobilization of less soluble mineral particles that clogged the flow path. Analyses of core sections via electron microscopy, synchrotron-based X-ray diffraction imaging, and the first application of microbeam Ca K-edge X-ray absorption near edge structure, provided evidence that these occlusions were fragments from the host rock rather than secondary precipitates. X-ray computed tomography showed a significant loss of rock mass within preferential flow paths, suggesting that dissolution also removed critical asperities and caused mechanical closure of the fracture. The decrease in fracture permeability despite a net removal of material along the fracture pathway demonstrates a nonintuitive, inverse relationship between dissolution and permeability evolution in a fractured carbonate caprock.

  18. The Permeability Transition in Plant Mitochondria: The Missing Link

    PubMed Central

    Zancani, Marco; Casolo, Valentino; Petrussa, Elisa; Peresson, Carlo; Patui, Sonia; Bertolini, Alberto; De Col, Valentina; Braidot, Enrico; Boscutti, Francesco; Vianello, Angelo

    2015-01-01

    The synthesis of ATP in mitochondria is dependent on a low permeability of the inner membrane. Nevertheless, mitochondria can undergo an increased permeability to solutes, named permeability transition (PT) that is mediated by a permeability transition pore (PTP). PTP opening requires matrix Ca2+ and leads to mitochondrial swelling and release of intramembrane space proteins (e.g., cytochrome c). This feature has been initially observed in mammalian mitochondria and tentatively attributed to some components present either in the outer or inner membrane. Recent works on mammalian mitochondria point to mitochondrial ATP synthase dimers as physical basis for PT, a finding that has been substantiated in yeast and Drosophila mitochondria. In plant mitochondria, swelling and release of proteins have been linked to programmed cell death, but in isolated mitochondria PT has been observed in only a few cases and in plant cell cultures only indirect evidence is available. The possibility that mitochondrial ATP synthase dimers could function as PTP also in plants is discussed here on the basis of the current evidence. Finally, a hypothetical explanation for the origin of PTP is provided in the framework of molecular exaptation. PMID:26697057

  19. Measuring Clogging with Pressure Transducers in Permeable Pavement Strips

    EPA Science Inventory

    Two issues that have a negative affect on the long term hydrologic performance of permeable pavement systems are surface clogging and clogging at the interface with the underlying soil. Surface clogging limits infiltration capacity and results in bypass if runoff rate exceeds in...

  20. PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF INORGANIC CONTAMINANTS

    EPA Science Inventory

    The permeable reactive barrier (PRB) technology is an in-situ approach for groundwater remediation that couples subsurface flow management with a passive chemical or biochemical treatment zone. The development and application of the PRB technology has progressed over the last de...

  1. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS: LESSONS LEARNED

    EPA Science Inventory

    This presentation will provide an overview of research efforts at EPA on the application, monitoring, and performance of Permeable Reactive Barriers (PRBs) for groundwater restoration. Over the past 10 years, research projects conducted by research staff at EPA's National Risk M...

  2. Hot spices influence permeability of human intestinal epithelial monolayers.

    PubMed

    Jensen-Jarolim, E; Gajdzik, L; Haberl, I; Kraft, D; Scheiner, O; Graf, J

    1998-03-01

    Indirect evidence suggests that hot spices may interact with epithelial cells of the gastrointestinal tract to modulate their transport properties. Using HCT-8 cells, a cell line from a human ileocoecal carcinoma, we studied the effects of spices on transepithelial electrical resistance (TER), permeability for fluorescein isothiocyanate (FITC)-labeled dextrans with graded molecular weight, and morphological alterations of tight junctions by immunofluorescence using an anti-ZO-1 antibody, a marker for tight junction integrity. Two different reactivity patterns were observed: paprika and cayenne pepper significantly decreased the TER and increased permeability for 10-, 20- and 40-kDa dextrans but not for -70 kDa dextrans. Simultaneously, tight junctions exhibited a discontinuous pattern. Applying extracts from black or green pepper, bay leaf or nutmeg increased the TER and macromolecular permeability remained low. Immunofluorescence ZO-1 staining was preserved. In accordance with the above findings, capsaicin transiently reduced resistance and piperine increased resistance, making them candidates for causing the effects seen with crude spice extracts. The observation that Solanaceae spices (paprika, cayenne pepper) increase permeability for ions and macromolecules might be of pathophysiological importance, particularly with respect to food allergy and intolerance.

  3. Dissolution-Driven Permeability Reduction of a Fractured Carbonate Caprock

    PubMed Central

    Ellis, Brian R.; Fitts, Jeffrey P.; Bromhal, Grant S.; McIntyre, Dustin L.; Tappero, Ryan; Peters, Catherine A.

    2013-01-01

    Abstract Geochemical reactions may alter the permeability of leakage pathways in caprocks, which serve a critical role in confining CO2 in geologic carbon sequestration. A caprock specimen from a carbonate formation in the Michigan sedimentary Basin was fractured and studied in a high-pressure core flow experiment. Inflowing brine was saturated with CO2 at 40°C and 10 MPa, resulting in an initial pH of 4.6, and had a calcite saturation index of −0.8. Fracture permeability decreased during the experiment, but subsequent analyses did not reveal calcite precipitation. Instead, experimental observations indicate that calcite dissolution along the fracture pathway led to mobilization of less soluble mineral particles that clogged the flow path. Analyses of core sections via electron microscopy, synchrotron-based X-ray diffraction imaging, and the first application of microbeam Ca K-edge X-ray absorption near edge structure, provided evidence that these occlusions were fragments from the host rock rather than secondary precipitates. X-ray computed tomography showed a significant loss of rock mass within preferential flow paths, suggesting that dissolution also removed critical asperities and caused mechanical closure of the fracture. The decrease in fracture permeability despite a net removal of material along the fracture pathway demonstrates a nonintuitive, inverse relationship between dissolution and permeability evolution in a fractured carbonate caprock. PMID:23633894

  4. Nutrient Infiltrate Concentrations from Three Permeable Pavement Types

    EPA Science Inventory

    While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha...

  5. Amorphous azithromycin with improved aqueous solubility and intestinal membrane permeability.

    PubMed

    Aucamp, Marique; Odendaal, Roelf; Liebenberg, Wilna; Hamman, Josias

    2015-01-01

    Azithromycin (AZM) is a poorly soluble macrolide antibacterial agent. Its low solubility is considered as the major contributing factor to its relatively low oral bioavailability. The aim of this study was to improve the solubility of this active pharmaceutical ingredient (API) by preparing an amorphous form by quench cooling of the melt and to study the influence of the improved solubility on membrane permeability. The amorphous azithromycin (AZM-A) exhibited a significant increase in water solubility when compared to the crystalline azithromycin dihydrate (AZM-DH). The influence that the improved solubility could have on membrane permeability was also studied. The apparent permeability coefficient (Papp) values of AZM-A were statistically significantly higher (p < 0.05) than crystalline AZM-DH at pH values of 6.8 and 7.2. The results therefore indicated that the improved solubility of AZM in the amorphous form also produced improved permeability across excised intestinal tissue at physiological pH values found in the small intestine.

  6. Permeable Reactive Barriers for Treatment of Cr6

    EPA Science Inventory

    Several options are available for treatment of hexavalent chromium (Cr(VI)) in groundwater using the permeable reactive barrier (PRB) approach. They include conventional trench-and-fill systems, chemical redox curtains, and organic carbon redox curtains. Each of these PRB syste...

  7. MICROBIAL CHARACTERIZATION OF MANURE BASED PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    The implementation of permeable reactive barriers (PRB) provides a viable option for the remediation of contaminants of environmental significance such as dissolved metals (i.e., chromium), chlorinated solvents, and nitrate/ammonia. The designs of PRBs are usually based on the a...

  8. Demonstrations of Magnetic Phenomena: Measuring the Air Permeability Using Tablets

    ERIC Educational Resources Information Center

    Lara, V. O. M.; Amaral, D. F.; Faria, D.; Vieira, L. P.

    2014-01-01

    We use a tablet to experimentally determine the dependencies of the magnetic field (B) on the electrical current and the axial distance from a coil (z). Our data shows good precision on the inverse cubic dependence of the magnetic field on the axial distance, B?z[superscript -3]. We obtain the value of air permeability µ[subscript air] with good…

  9. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SUBDIVISION AND STABILITY SPECIAL RULES PERTAINING TO SPECIFIC VESSEL TYPES Special Rules Pertaining to Mobile Offshore Drilling Units §...

  10. Dissolution-Driven Permeability Reduction of a Fractured Carbonate Caprock

    SciTech Connect

    Ellis, Brian R.; Fitts, Jeffrey P.; Bromhal, Grant S.; McIntyre, Dustin L.; Tappero, Ryan; Peters, Catherine A.

    2013-04-01

    Geochemical reactions may alter the permeability of leakage pathways in caprocks, which serve a critical role in confining CO{sub 2} in geologic carbon sequestration. A caprock specimen from a carbonate formation in the Michigan sedimentary Basin was fractured and studied in a high-pressure core flow experiment. Inflowing brine was saturated with CO{sub 2} at 40°C and 10MPa, resulting in an initial pH of 4.6, and had a calcite saturation index of -0.8. Fracture permeability decreased during the experiment, but subsequent analyses did not reveal calcite precipitation. Instead, experimental observations indicate that calcite dissolution along the fracture pathway led to mobilization of less soluble mineral particles that clogged the flow path. Analyses of core sections via electron microscopy, synchrotron-based X-ray diffraction imaging, and the first application of microbeam Ca K-edge X-ray absorption near edge structure, provided evidence that these occlusions were fragments from the host rock rather than secondary precipitates. X-ray computed tomography showed a significant loss of rock mass within preferential flow paths, suggesting that dissolution also removed critical asperities and caused mechanical closure of the fracture. The decrease in fracture permeability despite a net removal of material along the fracture pathway demonstrates a nonintuitive, inverse relationship between dissolution and permeability evolution in a fractured carbonate caprock.

  11. Ammonia recovery from livestock waste using gas permeable membrane technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This presentation shows new methods and systems being developed for reducing ammonia emissions from livestock waste and recovering concentrated liquid nitrogen that could be sold as fertilizer. These systems use gas-permeable membranes as components of new processes to capture and recover the ammoni...

  12. Ammonia recovery from livestock wastewater with gas permeable membranes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This presentation shows new methods and systems being developed for reducing ammonia emissions from livestock waste and recovering concentrated liquid nitrogen that could be sold as fertilizer. These systems use gas-permeable membranes as components of new processes to capture and recover the ammoni...

  13. Permeability changes in coal resulting from gas desorption

    SciTech Connect

    Levine, J.R.; Johnson, P.M.

    1992-01-01

    Research continued on the study of coal permeability and gas desorption. This quarter, most of the effort involved identifying problems with the microbalance and then getting it repaired. Measurement of the amount of gas adsorbed with the microbalance involved corrections for the buoyancy change with pressure and several experiments with helium were made to determine this correction.

  14. Iron abundance and magnetic permeability of the moon

    NASA Technical Reports Server (NTRS)

    Parkin, C. W.; Daily, W. D.; Dyal, P.

    1974-01-01

    A set of simultaneous data from the Apollo 12 lunar surface magnetometer and the Explorer 35 Ames magnetometer are used to construct a whole-moon hysteresis curve, from which a new value of global lunar permeability is determined to be mu = 1.012 + or - 0.006. The corresponding global induced dipole moment is 2.1 x 10 to the 18th power gauss-cucm for typical inducing fields of .1000 gauss in the lunar environment. From the permeability measurement, lunar free iron abundance is determined to be 2.5 + or - 2.0 wt. %. Total iron abundance is calculated for two assumed compositional models of the lunar interior: a free iron/orthopyroxene lunar composition and a free iron/olivine composition. The overall lunar total iron abundance is determined to be 9.0 + or - 4.7 wt. %. Other lunar models with a small iron core and with a shallow iron-rich layer are discussed in light of the measured global permeability. Effects on permeability and iron content calculations due to a possible lunar ionosphere are also considered.

  15. An asymptotic model of seismic reflection from a permeable layer

    SciTech Connect

    Silin, D.; Goloshubin, G.

    2009-10-15

    Analysis of compression wave propagation in a poroelastic medium predicts a peak of reflection from a high-permeability layer in the low-frequency end of the spectrum. An explicit formula expresses the resonant frequency through the elastic moduli of the solid skeleton, the permeability of the reservoir rock, the fluid viscosity and compressibility, and the reservoir thickness. This result is obtained through a low-frequency asymptotic analysis of Biot's model of poroelasticity. A review of the derivation of the main equations from the Hooke's law, momentum and mass balance equations, and Darcy's law suggests an alternative new physical interpretation of some coefficients of the classical poroelasticity. The velocity of wave propagation, the attenuation factor, and the wave number, are expressed in the form of power series with respect to a small dimensionless parameter. The absolute value of this parameter is equal to the product of the kinematic reservoir fluid mobility and the wave frequency. Retaining only the leading terms of the series leads to explicit and relatively simple expressions for the reflection and transmission coefficients for a planar wave crossing an interface between two permeable media, as well as wave reflection from a thin highly-permeable layer (a lens). Practical applications of the obtained asymptotic formulae are seismic modeling, inversion, and at-tribute analysis.

  16. MEAUSREMENT OF THE SURFACE PERMEABILITY OF BASEMENT CONCRETES

    EPA Science Inventory

    The report discusses the development, testing, and use of a portable surface permeameter suitable for field use in measuring the surface permeability of concrete in new houses. he permeameter measures the airflow induced by a pressure difference across a temporary test seal appli...

  17. Mechanisms of formation damage in matrix-permeability geothermal wells

    SciTech Connect

    Bergosh, J.L.; Wiggins, R.B.; Enniss, D.O.

    1982-04-01

    Tests were conducted to determine mechanisms of formation damage that can occur in matrix permeability geothermal wells. Two types of cores were used in the testing, actual cores from the East Mesa Well 78-30RD and cores from a fairly uniform generic sandstone formation. Three different types of tests were run. The East Mesa cores were used in the testing of the sensitivity of core to filtrate chemistry. The tests began with the cores exposed to simulated East Mesa brine and then different filtrates were introduced and the effects of the fluid contrast on core permeability were measured. The East Mesa cores were also used in the second series of tests which tested formation sandstone cores were used in the third test series which investigated the effects of different sizes of entrained particles in the fluid. Tests were run with both single-particle sizes and distributions of particle mixes. In addition to the testing, core preparation techniques for simulating fracture permeability were evaluated. Three different fracture formation mechanisms were identified and compared. Measurement techniques for measuring fracture size and permeability were also developed.

  18. COLLECTION OF DESIGN DATA: SITE CHARACTERIZATION FOR PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Permeable reactive barriers (PRBs) for the restoration of contaminated ground water are no longer innovative. PRBs have evolved from innovative to accepted, standard practice, for the containment and treatment of a variety of contaminants in ground water. Like any remedial tech...

  19. Evaluation of unsaturated zone air permeability through pneumatic tests

    USGS Publications Warehouse

    Baehr, Arthur L.; Hult, Marc F.

    1991-01-01

    Predicting the steady state distribution of air pressure in the unsaturated zone resulting from a pneumatic test provides a method for determining air-phase permeability. This technique is analogous to the inverse problem of well hydraulics; however, air flow is more complicated than ground water flow because of air compressibility, the Klinkenberg effect, variations in air density and viscosity that result from temperature fluctuations in the unsaturated zone and the possibility of inducing water movement during the pneumatic test. An analysis of these complicating factors reveals that, when induced water movement can be neglected, a linear version of the airflow equation can provide an appropriate approximation for the purpose of determining air-phase permeability. Two analytical solutions for steady state, two-dimensional, axisymmetric airflow to a single well partially screened in the unsaturated zone are developed. One solution applies where there is a stratum of relatively low air permeability, separating the stratum in which the well is completed, from the atmosphere. The other solution applies where there is no separating stratum between the domain and atmosphere. In both situations the water table forms the lower horizontal boundary. Applications of both solutions to determine air permeability from data collected during pneumatic tests are presented.

  20. Salmonella Rapidly Regulates Membrane Permeability To Survive Oxidative Stress

    PubMed Central

    van der Heijden, Joris; Reynolds, Lisa A.; Deng, Wanyin; Mills, Allan; Scholz, Roland; Imami, Koshi; Foster, Leonard J.; Duong, Franck

    2016-01-01

    ABSTRACT The outer membrane (OM) of Gram-negative bacteria provides protection against toxic molecules, including reactive oxygen species (ROS). Decreased OM permeability can promote bacterial survival under harsh circumstances and protects against antibiotics. To better understand the regulation of OM permeability, we studied the real-time influx of hydrogen peroxide in Salmonella bacteria and discovered two novel mechanisms by which they rapidly control OM permeability. We found that pores in two major OM proteins, OmpA and OmpC, could be rapidly opened or closed when oxidative stress is encountered and that the underlying mechanisms rely on the formation of disulfide bonds in the periplasmic domain of OmpA and TrxA, respectively. Additionally, we found that a Salmonella mutant showing increased OM permeability was killed more effectively by treatment with antibiotics. Together, these results demonstrate that Gram-negative bacteria regulate the influx of ROS for defense against oxidative stress and reveal novel targets that can be therapeutically targeted to increase bacterial killing by conventional antibiotics. PMID:27507830

  1. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false High permeability hemodialysis system. 876.5860 Section 876.5860 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Therapeutic Devices § 876.5860 High...

  2. Trench infiltration for managed aquifer recharge to permeable bedrock

    USGS Publications Warehouse

    Heilweil, V.M.; Watt, D.E.

    2011-01-01

    Managed aquifer recharge to permeable bedrock is increasingly being utilized to enhance resources and maintain sustainable groundwater development practices. One such target is the Navajo Sandstone, an extensive regional aquifer located throughout the Colorado Plateau of the western United States. Spreading-basin and bank-filtration projects along the sandstone outcrop's western edge in southwestern Utah have recently been implemented to meet growth-related water demands. This paper reports on a new cost-effective surface-infiltration technique utilizing trenches for enhancing managed aquifer recharge to permeable bedrock. A 48-day infiltration trench experiment on outcropping Navajo Sandstone was conducted to evaluate this alternative surface-spreading artificial recharge method. Final infiltration rates through the bottom of the trench were about 0.5 m/day. These infiltration rates were an order of magnitude higher than rates from a previous surface-spreading experiment at the same site. The higher rates were likely caused by a combination of factors including the removal of lower permeability soil and surficial caliche deposits, access to open vertical sandstone fractures, a reduction in physical clogging associated with silt and biofilm layers, minimizing viscosity effects by maintaining isothermal conditions, minimizing chemical clogging caused by carbonate mineral precipitation associated with algal photosynthesis, and diminished gas clogging associated with trapped air and biogenic gases. This pilot study illustrates the viability of trench infiltration for enhancing surface spreading of managed aquifer recharge to permeable bedrock. ?? 2010.

  3. Transient receptor potential channels and regulation of lung endothelial permeability

    PubMed Central

    2013-01-01

    Abstract This review highlights our current knowledge regarding expression of transient receptor potential (TRP) cation channels in lung endothelium and evidence for their involvement in regulation of lung endothelial permeability. Six mammalian TRP families have been identified and organized on the basis of sequence homology: TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPML (mucolipin), TRPP (polycystin), and TRPA (ankyrin). To date, only TRPC1/4, TRPC6, TRPV4, and TRPM2 have been extensively studied in lung endothelium. Calcium influx through each of these channels has been documented to increase lung endothelial permeability, although their channel-gating mechanisms, downstream signaling mechanisms, and impact on endothelial structure and barrier integrity differ. While other members of the TRPC, TRPV, and TRPM families may be expressed in lung endothelium, we have little or no evidence linking these to regulation of lung endothelial permeability. Further, neither the expression nor functional role(s) of any TRPML, TRPP, and TRPA family members has been studied in lung endothelium. In addition to this assessment organized by TRP channel family, we also discuss TRP channels and lung endothelial permeability from the perspective of lung endothelial heterogeneity, using outcomes of studies focused on TRPC1/4 and TRPV4 channels. The diversity within the TRP channel family and the relative paucity of information regarding roles of a number of these channels in lung endothelium make this field ripe for continued investigation. PMID:25006396

  4. Investigation of the feasibility of developing low permeability polymeric films

    NASA Technical Reports Server (NTRS)

    Hoggatt, J. T.

    1971-01-01

    The feasibility of reducing the gas permeability rate of Mylar and Kapton films without drastically effecting their flexibility characteristics at cryogenic temperatures was considered. This feasibility was established using a concept of diffusion bonding two layers of metallized films together forming a film-metal-film sandwich laminate. The permeability of kapton film to gaseous helium was reduced from a nominal ten = to the minus 9 power cc-mm/sq cm sec. cm Hg to ten to the minus 13 power cc-mm/ sq cm - sec. cm Hg with some values as low as ten to the minus 15 power cc - mm/sq cm m-sec - cm Hg being obtained. Similar reductions occurred in the liquid hydrogen permeability at -252 C. In the course of the program the permeability, flexibility and bond strength of plain, metalized and diffusion bond film were determined at +25 C, -195 C and -252 C. The cryogenic flexibility of Kapton film was reduced slightly due to the metallization process but no additional loss in flexibility resulted from the diffusion bonding process.

  5. Aeroperformance and Acoustics of the Nozzle with Permeable Shell

    NASA Technical Reports Server (NTRS)

    Gilinsky, M.; Blankson, I. M.; Chernyshev, S. A.; Chernyshev, S. A.

    1999-01-01

    Several simple experimental acoustic tests of a spraying system were conducted at the NASA Langley Research Center. These tests have shown appreciable jet noise reduction when an additional cylindrical permeable shell was employed at the nozzle exit. Based on these results, additional acoustic tests were conducted in the anechoic chamber AK-2 at the Central Aerohydrodynamics Institute (TsAGI, Moscow) in Russia. These tests examined the influence of permeable shells on the noise from a supersonic jet exhausting from a round nozzle designed for exit Mach number, M (sub e)=2.0, with conical and Screwdriver-shaped centerbodies. The results show significant acoustic benefits of permeable shell application especially for overexpanded jets by comparison with impermeable shell application. The noise reduction in the overall pressure level was obtained up to approximately 5-8%. Numerical simulations of a jet flow exhausting from a convergent-divergent nozzle designed for exit Mach number, M (sub e)=2.0, with permeable and impermeable shells were conducted at the NASA LaRC and Hampton University. Two numerical codes were used. The first is the NASA LaRC CFL3D code for accurate calculation of jet mean flow parameters on the basis of a full Navier-Stokes solver (NSE). The second is the numerical code based on Tam's method for turbulent mixing noise (TMN) calculation. Numerical and experimental results are in good qualitative agreement.

  6. Two Relations to Estimate Membrane Permeability Using Milestoning

    PubMed Central

    2016-01-01

    Prediction of passive permeation rates of solutes across lipid bilayers is important to drug design, toxicology, and other biological processes such as signaling. The inhomogeneous solubility-diffusion (ISD) equation is traditionally used to relate the position-dependent potential of mean force and diffusivity to the permeability coefficient. The ISD equation is derived via the Smoluchowski equation and assumes overdamped system dynamics. It has been suggested that the complex membrane environment may exhibit more complicated damping conditions. Here we derive a variant of the inhomogeneous solubility diffusion equation as a function of the mean first passage time (MFPT) and show how milestoning, a method that can estimate kinetic quantities of interest, can be used to estimate the MFPT of membrane crossing and, by extension, the permeability coefficient. We further describe a second scheme, agnostic to the damping condition, to estimate the permeability coefficient from milestoning results or other methods that compute a probability of membrane crossing. The derived relationships are tested using a one-dimensional Langevin dynamics toy system confirming that the presented theoretical methods can be used to estimate permeabilities given simulation and milestoning results. PMID:27154639

  7. Predicting chemically-induced skin reactions. Part II: QSAR models of skin permeability and the relationships between skin permeability and skin sensitization

    SciTech Connect

    Alves, Vinicius M.; Muratov, Eugene; Fourches, Denis; Strickland, Judy; Kleinstreuer, Nicole; Tropsha, Alexander

    2015-04-15

    Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, we found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R{sup 2} = 0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q{sup 2}{sub ext} = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. - Highlights: • It was compiled the largest publicly-available skin permeability dataset. • Predictive QSAR models were developed for skin permeability. • No concordance between skin

  8. A study of the osmotic characteristics, water permeability, and cryoprotectant permeability of human vaginal immune cells

    PubMed Central

    Shu, Zhiquan; Hughes, Sean M.; Fang, Cifeng; Huang, Jinghua; Fu, Baiwen; Zhao, Gang; Fialkow, Michael; Lentz, Gretchen; Hladik, Florian; Gao, Dayong

    2016-01-01

    Cryopreservation of specimens taken from the genital tract of women is important for studying mucosal immunity during HIV prevention trials. However, it is unclear whether the current, empirically developed cryopreservation procedures for peripheral blood cells are also ideal for genital specimens. The optimal cryopreservation protocol depends on the cryobiological features of the cells. Thus, we obtained tissue specimens from vaginal repair surgeries, isolated and flow cytometry-purified immune cells, and determined fundamental cryobiological characteristics of vaginal CD3+ T cells and CD14+ macrophages using a microfluidic device. The osmotically inactive volumes of the two cell types (Vb) were determined relative to the initial cell volume (V0) by exposing the cells to hypotonic and hypertonic saline solutions, evaluating the equilibrium volume, and applying the Boyle van't Hoff relationship. The cell membrane permeability to water (Lp) and to four different cryoprotective agent (CPA) solutions (Ps) at room temperature were also measured. Results indicated Vb values of 0.516 V0 and 0.457 V0 for mucosal T cells and macrophages, respectively. Lp values at room temperature were 0.196 and 0.295 μm/min/atm for T cells and macrophages, respectively. Both cell types had high Ps values for the three CPAs, dimethyl sulfoxide (DMSO), propylene glycol (PG) and ethylene glycol (EG) (minimum of 0.418 × 10−3 cm/min), but transport of the fourth CPA, glycerol, occurred 50–150 times more slowly. Thus, DMSO, PG, and EG are better options than glycerol in avoiding severe cell volume excursion and osmotic injury during CPA addition and removal for cryopreservation of human vaginal immune cells. PMID:26976225

  9. A study of the osmotic characteristics, water permeability, and cryoprotectant permeability of human vaginal immune cells.

    PubMed

    Shu, Zhiquan; Hughes, Sean M; Fang, Cifeng; Huang, Jinghua; Fu, Baiwen; Zhao, Gang; Fialkow, Michael; Lentz, Gretchen; Hladik, Florian; Gao, Dayong

    2016-04-01

    Cryopreservation of specimens taken from the genital tract of women is important for studying mucosal immunity during HIV prevention trials. However, it is unclear whether the current, empirically developed cryopreservation procedures for peripheral blood cells are also ideal for genital specimens. The optimal cryopreservation protocol depends on the cryobiological features of the cells. Thus, we obtained tissue specimens from vaginal repair surgeries, isolated and flow cytometry-purified immune cells, and determined fundamental cryobiological characteristics of vaginal CD3(+) T cells and CD14(+) macrophages using a microfluidic device. The osmotically inactive volumes of the two cell types (Vb) were determined relative to the initial cell volume (V0) by exposing the cells to hypotonic and hypertonic saline solutions, evaluating the equilibrium volume, and applying the Boyle van't Hoff relationship. The cell membrane permeability to water (Lp) and to four different cryoprotective agent (CPA) solutions (Ps) at room temperature were also measured. Results indicated Vb values of 0.516 V0 and 0.457 V0 for mucosal T cells and macrophages, respectively. Lp values at room temperature were 0.196 and 0.295 μm/min/atm for T cells and macrophages, respectively. Both cell types had high Ps values for the three CPAs, dimethyl sulfoxide (DMSO), propylene glycol (PG) and ethylene glycol (EG) (minimum of 0.418 × 10(-3) cm/min), but transport of the fourth CPA, glycerol, occurred 50-150 times more slowly. Thus, DMSO, PG, and EG are better options than glycerol in avoiding severe cell volume excursion and osmotic injury during CPA addition and removal for cryopreservation of human vaginal immune cells. PMID:26976225

  10. Permeability-Porosity Relationships in Deep Sea Hydrothermal Vent Deposits

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Gittings, H.; Tivey, M. K.

    2003-12-01

    To map out the thermal and chemical regimes within vent deposits where micro-and macro-organisms reside requires accurate modeling of mixing and reaction between hydrothermal fluid and seawater within the vent structures. However, a critical piece of information, quantitative knowledge of the permeability of vent deposits, and how it relates to porosity and pore geometry, is still missing. To address this, systematic laboratory measurements of permeability and porosity were conducted on 3 large vent structures from the Mothra Hydrothermal vent field on the Endeavor Segment of the Juan de Fuca Ridge. Twenty-five cylindrical cores with diameters of 2.54 cm and various lengths were taken from Phang (a tall sulfide-dominated spire that was not actively venting when sampled), Roane (a lower temperature spire with dense macrofaunal communities growing on its sides that was venting diffuse fluid of < 300° C) and Finn (an active black smoker with a well-defined inner conduit that was venting 302° C fluids prior to recovery (Delaney et al., 2000; Kelley et al, 2000)). Measurements were made to obtain porosity and permeability of these drill cores using a helium porosimeter (UltraPoreTM300) and a nitrogen permeameter (UltrapermTM400) from Core Laboratories Instruments. The porosimeter uses Boyle's law to determine pore volume from the expansion of a know mass of helium into a calibrated sample holder, whereas the permeameter uses Darcy's law to determine permeability by measuring the steady-state flow rate through the sample under a given pressure gradient. A moderate confining pressure of 1.38 MPa was applied during the measurements to prevent leakage between the sample surface and the sample holder. The permeability and porosity relationship is best described by two different power law relationships with exponents of ˜9 (group I) and ˜3 (group II), respectively. Microstructural observations suggest that the difference in the two permeability-porosity relationships

  11. Permeability Evolution and the Mechanisms of Porosity Change (Invited)

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Gribbin, J. L.; Tivey, M. K.

    2013-12-01

    Understanding subsurface fluid flow is of critical importance to such geological and engineering applications as faulting mechanics, hydrothermal venting and resource recovery. Mechanical, chemical and thermal loads can significantly alter microscopic pore geometry and thus affect macroscopic permeability. Recently, we measured the permeability and porosity of massive anhydrite deposits recovered from various seafloor hydrothermal vent fields. Together, these deposits comprise anhydrite samples that have undergone different stages of formation. For anhydrite samples with porosities greater than 5%, the dependence of permeability to porosity change is best characterized by a power-law relationship with an exponent n~9. At porosities less than 5%, a much gentler trend of n~1 is observed. These permeability-porosity relationships (PPRs) in anhydrite deposits are in stark contrast to those of Fontainebleau sandstone, a quartz arenite with various degrees of quartz cementation. Fontainebleau sandstone shows a power-law dependence of PPR with an exponent of n~3 for samples with porosities greater than 7%, and a much steeper trend of n~8 at low porosities [Bourbie and Zinszner, 1985]. Microstructural analysis and numerical models suggest that the significant loss in pore connectivity below 7% is responsible for the steeper PPR trend in Fontainebleau sandstone [Zhu et al., 1995]. In anhydrite deposits, petrographic analyses show evidence for both dissolution and precipitation, consistent with the observed PPRs resulting from pore-size controlled solubility. Precipitation of anhydrite takes place preferentially in large pores within the anhydrite deposits, with precipitation limited in small pores, which is proposed to be due to the change in interfacial energy of the growing crystal (e.g., as described by Emmanuel and Ague [2009]). With abundant large voids in high porosity anhydrite samples, the growth of sulfates would result in a drastic loss of pore connectivity and

  12. Role of different biodegradable polymers on the permeability of ciprofloxacin

    PubMed Central

    Chakraborti, Chandra Kanti; Sahoo, Subhashree; Behera, Pradipta Kumar

    2014-01-01

    Since permeability across biological membranes is a key factor in the absorption and distribution of drugs, drug permeation characteristics of three oral suspensions of ciprofloxacin were designed and compared. The three suspensions of ciprofloxacin were prepared by taking biodegradable polymers such as carbopol 934, carbopol 940, and hydroxypropyl methylcellulose (HPMC). The permeability study was performed by using a Franz diffusion cell through both synthetic cellulose acetate membrane and excised goat gastrointestinal membranes in acidic as well as alkaline pH. To know the permeability of drug from control/formulations through different membranes in acidic/alkaline pH, cumulative percentage drug permeation, apparent permeability (Papp), flux, and enhancement ratio (ER) were calculated. Considering Papp and flux values of all formulations, it is evident that formulation containing HPMC was the most beneficial for improving permeation and diffusivity of ciprofloxacin even after 16 h. Hence, this preparation may be considered as the most suitable formulation to obtain prolonged release action of the drug. The ER values of all formulations, through excised goat intestinal mucosal membrane in alkaline pH, were higher than those formulations through goat stomach mucosal membrane in acidic pH. Enhancement ratio values of those formulations indicate that the permeability of the drug was more enhanced by the polymers in the intestinal part, leading to more bioavailability and prolonged action in that portion of the gastrointestinal tract. It may also be concluded from our results that HPMC containing formulation was the best suspension, which may show effective controlled release action. Even carbopol containing formulations might also produce controlled release action. PMID:25126536

  13. Permeability changes in layered sediments: impact of particle release.

    PubMed

    Blume, Theresa; Weisbrod, Noam; Selker, John S

    2002-01-01

    One of the mechanisms of sudden particle release from grain surfaces in natural porous media is a decrease in salt concentration of the permeating fluid to below the critical salt concentration. Particle release can cause a change in hydraulic conductivity of the matrix, either by washing out the fines and thus increasing the pore sizes or by the plugging of pore constrictions. The phenomenon of permeability changes as a result of particle detachment was investigated in a series of column experiments. Coarse and fine sediments from the Hanford Formation in southeast Washington were tested. Columns were subject to a pulse of highly saline solution (NaNO3) followed by a fresh water shock causing particle release. Outflow rates and changes in hydraulic head as well as electric conductivity and pH were monitored over time. No permeability decrease occurred within the coarse matrix alone. However, when a thin layer of fine sediment was embedded within the coarse material (mimicking field conditions at the Hanford site), permeability irreversibly decreased to 10% to 20% of the initial value. Evidence suggests that most of this permeability decrease was a result of particles detached within the fine layer and its subsequent clogging. An additional observation was a sudden increase in pH in the outflow solution, generated in situ during the fresh water shock. Because layered systems are common in natural settings, our results suggest that alteration between sodium solution and fresh water can lead to particle release and subsequently reduce the overall permeability of the matrix. PMID:12236259

  14. Measuring the vertical permeability of horizontally- stratified sedimentary rocks

    SciTech Connect

    Novakowski, K.S.; Lapcevic, P.A. ); Reichart, T.M. )

    1993-03-01

    The vertical permeability of horizontally stratified rocks is usually assumed to be significantly less than the permeability of horizontal structural features such as bedding plane partings and sheeting structure. Consequently it is also assumed that this type of media provides suitable vertical barriers to the migration of both aqueous and non-aqueous phase groundwater contaminants. To investigate this assumption, a site adjacent to an inactive dolostone quarry was instrumented using nine boreholes drilled to a depth of approximately 25 m in a 30 x 30 m area. The area is immediately underlain by flat-lying thick-bedded dolostones of Middle-Silurian age. Six of the boreholes were drilled at angle of 45[degree] to intersect two vertical fracture sets oriented at 020[degree] and 110[degree] which were identified by mapping the fractures in the quarry. Detailed hydraulic tests (constant-head method) were conducted in each of the boreholes using a packer spacing of 0.5 m to determine the hydraulic properties of the individual horizontal and vertical fractures and fracture zones. In addition, four pumping tests were conducted in which a fracture zone in one of the vertical boreholes was shut-in and pumped and the hydraulic response was monitored in the observation boreholes using pressure transducer installed in 15 intervals isolated with multiple-packer strings. The results of the constant-head tests show that although the groundwater flow system in the dolostone is dominated by 3--4 horizontal fracture zones, the average permeability of the vertical fractures is only one order of magnitude less than the average permeability of the horizontal fractures. However, this aspect of the flow system is not detected using pumping tests, the results of which suggest that the average permeability is 3--4 orders of magnitude less in the vertical direction.

  15. Tritium Permeability of Incoloy 800H and Inconel 617

    SciTech Connect

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2011-09-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950 C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm) - three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  16. Tritium Permeability of Incoloy 800H and Inconel 617

    SciTech Connect

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2012-07-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950°C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm)—three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  17. Endothelial glycocalyx dysfunction in disease: albuminuria and increased microvascular permeability.

    PubMed

    Salmon, Andrew H J; Satchell, Simon C

    2012-03-01

    Appreciation of the glomerular microcirculation as a specialized microcirculatory bed, rather than as an entirely separate entity, affords important insights into both glomerular and systemic microvascular pathophysiology. In this review we compare regulation of permeability in systemic and glomerular microcirculations, focusing particularly on the role of the endothelial glycocalyx, and consider the implications for disease processes. The luminal surface of vascular endothelium throughout the body is covered with endothelial glycocalyx, comprising surface-anchored proteoglycans, supplemented with adsorbed soluble proteoglycans, glycosaminoglycans and plasma constituents. In both continuous and fenestrated microvessels, this endothelial glycocalyx provides resistance to the transcapillary escape of water and macromolecules, acting as an integral component of the multilayered barrier provided by the walls of these microvessels (ie acting in concert with clefts or fenestrae across endothelial cell layers, basement membranes and pericytes). Dysfunction of any of these capillary wall components, including the endothelial glycocalyx, can disrupt normal microvascular permeability. Because of its ubiquitous nature, damage to the endothelial glycocalyx alters the permeability of multiple capillary beds: in the glomerulus this is clinically apparent as albuminuria. Generalized damage to the endothelial glycocalyx can therefore manifest as both albuminuria and increased systemic microvascular permeability. This triad of altered endothelial glycocalyx, albuminuria and increased systemic microvascular permeability occurs in a number of important diseases, such as diabetes, with accumulating evidence for a similar phenomenon in ischaemia-reperfusion injury and infectious disease. The detection of albuminuria therefore has implications for the function of the microcirculation as a whole. The importance of the endothelial glycocalyx for other aspects of vascular function

  18. Intestinal permeability in patients with coeliac disease and dermatitis herpetiformis.

    PubMed Central

    Bjarnason, I; Marsh, M N; Price, A; Levi, A J; Peters, T J

    1985-01-01

    Intestinal permeability was investigated in patients with coeliac disease and dermatitis herpetiformis by a 51Chromium-labelled ethylenediaminetetraacetate (51Cr-EDTA) absorption test and the results correlated with histomorphometric analysis and intraepithelial lymphocyte counts of jejunal biopsies. The mean (+/- SD) 24 hour urine excretion of 51Cr-EDTA in 34 healthy volunteers was 1.9 +/- 0.5% of the orally administered test dose. Patients with untreated coeliac disease (19) or untreated dermatitis herpetiformis (five) excreted significantly more 51Cr-EDTA than controls (5.9 +/- 2.7% and 4.6 +/- 2.1%, respectively, p less than 0.001) and all were outside the normal range of 1.0-2.6%. Patients with coeliac disease (42) treated for 6 months-23 years (mean 5 years) and patients with dermatitis herpetiformis (11) treated for 6 months-8 years (mean 3 years) excreted significantly more 51Cr-EDTA than controls, 4.2 +/- 2.4% p less than 0.0001 and 3.0 +/- 0.9% p less than 0.003 respectively. Eleven of 14 (79%) treated patients with coeliac disease with an entirely normal jejunal mucosae demonstrated abnormal intestinal permeability. Intestinal permeability did not correlate significantly with either the mucosal height/crypt depth ratio or intraepithelial lymphocyte counts in jejunal biopsies from patients with untreated or treated coeliac disease. The demonstration of a persistent increase in intestinal permeability in patients with both coeliac disease and dermatitis herpetiformis may suggest a common pathogenetic mechanism in both disorders. It is postulated that altered permeability may facilitate the entry of gluten or a fraction thereof into the lamina propria where it causes a cascade of immunological events. PMID:3934051

  19. Filtration and clogging of permeable pavement loaded by urban drainage.

    PubMed

    Sansalone, J; Kuang, X; Ying, G; Ranieri, V

    2012-12-15

    Permeable pavement, as a sustainable infrastructure material can promote hydrologic restoration, particulate matter (PM) and solute control. However, filtration and commensurate clogging are two aspects of continued interest and discussion. This study quantifies filtration and clogging of cementitious permeable pavement (CPP) for loadings from 50 to 200 mg/L of hetero-disperse sandy-silt PM. The CPP mix design provides a hetero-disperse pore size distribution (PSD)(pore), effective porosity (φ(e)) of 24% and median pore size of 658 μm with a standard deviation of 457 μm. The PM mass separation across the entire particle size distribution (PSD)(PM) exceeds 80%; with complete separation for PM greater than 300 μm and 50% separation for suspended PM. Turbidity is reduced (42-95%), and effluent is below 10 NTU in the first quartile of a loading period. Permeable pavement illustrates reductions in initial (clean-bed) hydraulic conductivity (k(0)) with loading time. For all PM loadings, k(0) (3.1 × 10(-1) mm/s) was reduced to 10(-4) mm/s for runoff loading durations from 100 to 250 h, respectively. Temporal hydraulic conductivity (k) follows exponential profiles. Maintenance by vacuuming and sonication illustrate that 96-99% of k(0) is recovered. Permeable pavement constitutive properties integrated with measured PM loads and a year of continuous rainfall-runoff simulation illustrate k reduction with historical loadings. Study results measure and model filtration and hydraulic conductivity phenomena as well as maintenance requirements of permeable pavement directly loaded by urban drainage.

  20. Permeability of lipid bilayers to amino acids and phosphate

    NASA Technical Reports Server (NTRS)

    Chakrabarti, A. C.; Deamer, D. W.

    1992-01-01

    Permeability coefficients for amino acid classes, including neutral, polar, hydrophobic, and charged species, were measured and compared with values for other ionic solutes such as phosphate. The rates of efflux of glycine, lysine, phenylalanine, serine and tryptophan were determined after they were passively entrapped in large unilamellar vesicles (LUVs) composed of egg phosphatidylcholine (EPC) or dimyristoylphosphatidylcholine (DMPC). The following permeability coefficients were obtained for: glycine, 5.7 x 10(-12) cm s-1 (EPC), 2.0 x 10(-11) cm s-1 (DMPC); serine, 5.5 x 10(-12) cm s-1 (EPC), 1.6 x 10(-11) cm s-1 (DMPC); lysine, 5.1 x 10(-12) cm s-1 (EPC), 1.9 x 10(-11) cm s-1 (DMPC); tryptophan, 4.1 x 10(-10) cm s-1 (EPC); and phenylalanine, 2.5 x 10(-10) cm s-1 (EPC). Decreasing lipid chain length increased permeability slightly, while variations in pH had only minor effects on the permeability coefficients of the amino acids tested. Phosphate permeability was in the range of 10(-12)-10(-13) cm s-1 depending on the pH of the medium. The values for the polar and charged amino acids were surprisingly similar to those previously measured for monovalent cations such as sodium and potassium, which are in the range of 10(-12)-10(-13) cm s-1, depending on conditions and the lipid species used. This observation suggests that the permeation rates for the neutral, polar and charged amino acids are controlled by bilayer fluctuations and transient defects, rather than partition coefficients and Born energy barriers. The results are relevant to the permeation of certain peptides into lipid bilayers during protein translocation and membrane biogenesis.

  1. Permeability & Grain Size Distribution of Wenchuan Earthquake Fault Rocks

    NASA Astrophysics Data System (ADS)

    Yang, X.; Chen, J.; Ma, S.

    2010-12-01

    Permeability and grain size distribution of fault rocks from two outcrops of Wenchuan earthquake fault zone were measured. The results show that the permeability (at 40MPa) varies obviously across the fault zone, from 10-13 m2 -10-15 m2 for fractured and shattered breccias, ~ 10-17 m2 for crushed breccias to 10-18 m2 - <10-19 m2 for fresh gouges and country rocks. Particle sizes dominate the permeability of the fault rocks. The more the percentage of fine particles is, the lower the permeability is. Due to the impermeable gouges and permeable fractured breccias, seismic fault zone is characterized by anisotropy for fluid flowing. Fluids cycle along fault zone easily if breccias are not cemented. Two methods, sieve weighting and laser analyzer, were combined to analyze the grain size distribution of the fault rocks. The measurements indicate that the slope of log(N) ~ log(d) changes at a critical diameter dc with 1 - 2 mm, which corresponds to grinding limit of rocks and may represent a change from grinding process to attrition one. The fractal dimension (D), calculated based on the grains with size larger than dc, of gouges is higher than 3.0 with the fresh gouges having the highest value (≥ 3.4), of crushed breccias ranges from 2.56 to 2.99, and of fractured and shattered breccias has the lowest value, about 2.63 in average. However, the fractal dimension matching smaller grains (> 2 mm) becomes much lower, ranging from 1.7 to 2.2. It is expected that the estimation of surface fracture energy associated with faulting is less than that we thought if the grain size distribution is considered.

  2. Acid tolerance, proton permeabilities, and membrane ATPases of oral streptococci.

    PubMed Central

    Bender, G R; Sutton, S V; Marquis, R E

    1986-01-01

    Differences in acid tolerance among representative oral streptococci were found to be related more closely to the dynamic permeabilities of the bacteria to protons than to differences in the sensitivities of cell membranes to gross damage caused by environmental acidification. For Streptococcus mutans GS-5, Streptococcus sanguis NCTC 10904, and Streptococcus salivarius ATCC 13419, gross membrane damage, indicated by the release of magnesium from whole cells, occurred at pH values below about 4 and was rapid and extensive at pH values of about 3 or less. A more aciduric, lactic acid bacterium, Lactobacillus casei ATCC 4646, was more resistant to environmental acidification, and gross membrane damage was evident only at pH values below 3. Assessments of the movements of protons into S. mutans cells after an acid pulse at various pH values indicated that permeability to protons was minimal at a pH value of about 5, at which the average half time for pH equilibration across the cell membrane was about 12 min. The corresponding values for the less aciduric organism S. sanguis were pH 7 and 8.2 min, and the values for the intermediate organism S. salivarius were pH 6 and 6.6 min. The ATPase inhibitor dicyclohexylcarbodiimide acted to increase markedly the permeability of each organism to protons, and this action indicated that permeability involved not only the passive inflow of protons but also active outflow through the proton-translocating membrane ATPase. Membranes were isolated from each of the bacteria, and pH profiles for ATPase activities indicated pH optima of about 7.5, 7.0, 6.0, and 5.0 for S. sanguis, S. salivarius, S. mutans, and L. casei, respectively. Thus, the pH profiles for the enzymes reflected the acid tolerances of the bacteria and the permeabilities of whole cells to protons. PMID:3015800

  3. Permeability of Candidate Stirling Heater Head Materials Measured

    NASA Technical Reports Server (NTRS)

    Freedman, Marc R.; Singh, Mrityunjay

    2005-01-01

    Researchers at the NASA Glenn Research Center are evaluating high-temperature materials for Stirling heater heads for second- and third-generation Stirling radioisotope power systems that would help to increase the system efficiency to 30 to 35 percent and the system specific power to 8 to 10+ W/kg. Ceramic materials could make it possible for the convertor hot-end temperature to be increased to 1050 to 1200 C, in comparison to the current 650 C with an Inconel 718 heater head. A hermetically sealed Stirling heater head must retain a constant internal pressure of nearly 400-psi helium (He) throughout its useful life (120,000 hr) at the design operating temperature. Therefore, He permeability was measured for eight potential materials and compared with the permeability of the current heater head material, Inconel 718. The eight materials included silicon nitride (Si3N4), silicon dioxide (SiO2), both sintered and chemical vapor deposited (CVD) silicon carbide (SiC), alumina (Al2O3), two types of melt-infiltrated (MI) SiC/SiC composites, and a carbon/SiC composite (C/SiC). Glenn submitted samples of each material to Porous Materials, Inc., Ithaca, New York, for permeability analysis. At room temperature and 30-psi He, four materials--Si3N4, Al2O3, SiO2, and sintered SiC--demonstrated lower permeability than Inconel 718. The CVD SiC and all the composite materials were significantly more permeable to He than the baseline material.

  4. Permeability of rapid prototyped artificial bone scaffold structures.

    PubMed

    Lipowiecki, Marcin; Ryvolová, Markéta; Töttösi, Ákos; Kolmer, Niels; Naher, Sumsun; Brennan, Stephen A; Vázquez, Mercedes; Brabazon, Dermot

    2014-11-01

    In this work, various three-dimensional (3D) scaffolds were produced via micro-stereolithography (µ-SLA) and 3D printing (3DP) techniques. This work demonstrates the advantages and disadvantages of these two different rapid prototyping methods for production of bone scaffolds. Compared to 3DP, SLA provides for smaller feature production with better dimensional resolution and accuracy. The permeability of these structures was evaluated experimentally and via numerical simulation utilizing a newly derived Kozeny-Carman based equation for intrinsic permeability. Both experimental and simulation studies took account of porosity percentage, pore size, and pore geometry. Porosity content was varied from 30% to 70%, pore size from 0.34 mm to 3 mm, and pore geometries of cubic and hexagonal closed packed were examined. Two different fluid viscosity levels of 1 mPa · s and 3.6 mPa · s were used. The experimental and theoretical results indicated that permeability increased when larger pore size, increased fluid viscosity, and higher percentage porosity were utilized, with highest to lowest degree of significance following the same order. Higher viscosity was found to result in permeabilities 2.2 to 3.3 times higher than for water. This latter result was found to be independent of pore morphology type. As well as demonstrating method for determining design parameters most beneficial for scaffold structure design, the results also illustrate how the variations in patient's blood viscosity can be extremely important in allowing for permeability through the bone and scaffold structures.

  5. The effect of air permeability and water vapor permeability of cleanroom clothing on physiological responses and wear comfort.

    PubMed

    Chen, Te-Hung; Chen, Wan-Ping; Wang, Mao-Jiun J

    2014-01-01

    The function of cleanroom clothing is to protect the product from contamination by people, and to dissipate electrostatic discharge. People in the cleanroom work environment often complain about the discomforts associated with the wearing of cleanroom clothing. The purpose of this study is to investigate the effect of air permeability and water vapor permeability of cleanroom clothing on the subject's physiological and subjective responses. Five male and five female subjects participated in this study. The experimental goal was to simulate the operator's regular tasks in a semiconductor manufacturing cleanroom. Each subject completed three treatment combinations with three different cleanroom clothing types. A three-factor experiment was designed (significance level p = 0.05). The independent variables included gender, cleanroom clothing, and duration. The dependent measures included heart rate, core temperature, skin temperature, micro-climate relative humidity, micro-climate temperature, and subjective responses. A total of 40 min was involved for each treatment condition. The results indicate that skin temperature, micro-climate temperature and micro-climate relative humidity were lower while wearing cleanroom clothing with high air permeability and high water vapor permeability. The significant gender difference was found in skin temperature. As the task time increased, the micro-climate temperature also increased but the micro-climate relative humidity decreased at first and then increased. In addition, the physiological responses showed significant positive correlations with the subjective perception of clothing comfort. The findings of this study may provide useful information for cleanroom clothing design and selection.

  6. Mechanism of dexamethasone suppression of brain tumor-associated vascular permeability in rats. Involvement of the glucocorticoid receptor and vascular permeability factor.

    PubMed Central

    Heiss, J D; Papavassiliou, E; Merrill, M J; Nieman, L; Knightly, J J; Walbridge, S; Edwards, N A; Oldfield, E H

    1996-01-01

    Brain tumor-associated cerebral edema arises because tumor capillaries lack normal blood-brain barrier function; vascular permeability factor (VPF, also known as vascular endothelial growth factor, VEGF) is a likely mediator of this phenomenon. Clinically, dexamethasone reduces brain tumor-associated vascular permeability through poorly understood mechanisms. Our goals were to determine if suppression of permeability by dexamethasone might involve inhibition of VPF action or expression, and if dexamethasone effects in this setting are mediated by the glucocorticoid receptor (GR). In two rat models of permeability (peripheral vascular permeability induced by intradermal injection of 9L glioma cell-conditioned medium or purified VPF, and intracerebral vascular permeability induced by implanted 9L glioma), dexamethasone suppressed permeability in a dose-dependent manner. Since 80% of the permeability-inducing activity in 9L-conditioned medium was removed by anti-VPF antibodies, we examined dexamethasone effects of VPF expression in 9L cells. Dexamethasone inhibited FCS- and PDGF-dependent induction of VPF expression. At all levels (intradermal, intracranial, and cell culture), dexamethasone effects were reversed by the GR antagonist mifepristone (RU486). Dexamethasone may decrease brain tumor-associated vascular permeability by two GR-dependent mechanisms: reduction of the response of the vasculature to tumor-derived permeability factors (including VPF), and reduction of VPF expression by tumor cells. PMID:8823305

  7. Technology Solutions Case Study: Moisture Durability of Vapor Permeable Insulating Sheathing

    SciTech Connect

    2013-10-01

    In this project, Building America team Building Science Corporation researched some of the ramifications of using exterior, vapor permeable insulation on retrofit walls with vapor permeable cavity insulation. Retrofit strategies are a key factor in reducing exterior building stock consumption.

  8. Nutrient infiltrate concentrations from three permeable pavement types.

    PubMed

    Brown, Robert A; Borst, Michael

    2015-12-01

    While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous asphalt (PA). Each permeable pavement type has four, 54.9-m(2), lined sections that direct all infiltrate into 5.7-m(3) tanks enabling complete volume collection and sampling. This paper highlights the results from a 12-month period when samples were collected from 13 rainfall/runoff events and analyzed for nitrogen species, orthophosphate, and organic carbon. Differences in infiltrate concentrations among the three permeable pavement types were assessed and compared with concentrations in rainwater samples and impervious asphalt runoff samples, which were collected as controls. Contrary to expectations based on the literature, the PA infiltrate had significantly larger total nitrogen (TN) concentrations than runoff and infiltrate from the other two permeable pavement types, indicating that nitrogen leached from materials in the PA strata. There was no significant difference in TN concentration between runoff and infiltrate from either PICP or PC, but TN in runoff was significantly larger than in the rainwater, suggesting meaningful inter-event dry deposition. Similar to other permeable pavement studies, nitrate was the dominant nitrogen species in the infiltrate. The PA infiltrate had significantly larger nitrite and ammonia concentrations than PICP and PC, and this was presumably linked to unexpectedly high pH in the PA infiltrate that greatly exceeded the optimal pH range for nitrifying bacteria. Contrary to the nitrogen results, the PA infiltrate had significantly smaller orthophosphate concentrations than in rainwater, runoff, and infiltrate from PICP

  9. Estimated bounds on rock permeability changes from THM Processes

    SciTech Connect

    Berge, P A; Blair, S C; Wang, H F

    1998-08-01

    We performed THM modeling to estimate bounds on permeability changes in the NFE. For our modeling, we used the TM three-dimensional (3-D) finite-difference code FLAC{sup 3D} version 2.0 (Itasca Consulting Group Inc. 1997) to compute changes in stress and displacement in an elastic model subjected to temperature changes over time. Output from TH modeling (Hardin et al., 1998, Chapter 3) using the code NUFT (Nitao 1993) provided the temperature changes for input to FLAC{sup 3D}. We then estimated how the stress changes could affect permeability. For this report, we chose to base our 3-D THM modeling on a coarser version of the 2-D model we ran for the work described in Chapter 4 of the Near-Field/Altered Zone Models Report (Hardin et al., 1998, Chapter 4). The grid and temperature field were based on those used by the TH code for 50 yr of heating for the reference Case 1 TH model calculated using Total System Performance Assessment-Viability Assessment (TSPA-VA) base-case properties, nominal infiltration, and a point-load repository design (Hardin et al., 1998, Chapter 3). The stress field rotated in the region between and below the drifts after 50 yr of heating. High vertical shear stresses were computed for these regions. The maximum computed displacement was about 7 cm, mainly vertical. Estimates of permeability changes were obtained by analyzing stresses, following a method we developed previously for 2-D models. In our 3-D modeling for this report, we only considered vertical and horizontal fractures. We extended our 2-D method to a simplified 3-D case. We conclude that widespread permeability enhancement is likely for fractures parallel to NS fracture set No.2, the vertical fractures that strike north-south, for regions above the drifts. In some regions just above the drifts, permeability may increase by a minimum of a factor of two and possibly more than a factor of four if slip also occurs along the vertical fractures in EW set No.1, the east-west fractures

  10. Stress Analysis and Permeability Testing of Cryogenic Composite Feed Line

    NASA Technical Reports Server (NTRS)

    Chu, Tsuchin Philip

    1999-01-01

    For the next generation Single-Stage-To-Orbit (SSTO) Reusable Launch Vehicle (RLV), the use of advanced composite materials is highly desirable and critical to the success of the mission. NASA Marshall Space Flight Center (MSFC) has been working with the aerospace industry for many years to develop and demonstrate the cryogenic composite propellant tanks and feed lines technologies. A 50.8-mm diameter composite feed line for the Clipper Graham (DCY.A) was developed and tested. The purpose of the program is to demonstrate the LH2 permeability, composite to composite and metal joints, as well as composite flange interface of the composite feed line. Stress analysis and permeability testing have been performed on this article. Recently, a larger composite feed line design is being investigated and developed at MSFC for potential use in future RLV. The diameter of the feed line is 203 mm and the overall length is approximately 2.2 meters. This one piece unlined feed line consists of three straight tubular sections joined by two 90 degree elbows. The material chosen is IM7/977-3 prepreg fabric. The lay-up pattern is [0/90, plus or minus 45]s and is built up to 18 plies to the flanges at both ends. A preliminary stress analysis has been conducted to identify potential critical stresses and to develop the finite element analysis (FEA) capability of composite feed lines. As expected, the critical stresses occurred at the rims of some flange holes and the onset of the tapered tubular sections. Further analysis is required to determine the loads, flange deflection, vibration, and combined maximum loads. Two permeability-testing apparatuses were also designed for both flat panel specimens and curved feed line sections after impact damage. A larger permeant gas exposed area is required to accurately determine the effect of impact damage on the permeability of the feed line materials. The flat panel tester was fabricated and assembled. Three test coupons were made of graphite

  11. Tensor Inversion of Intrinsic Permeabilities for Heterogeneous Reservoirs

    NASA Astrophysics Data System (ADS)

    Jiao, J.; Zhang, Y.

    2013-12-01

    An inverse method has been developed using hybrid formulations and coordinate transform techniques to simultaneously estimate multiple intrinsic permeability tensors (k), flow field, and boundary conditions for a heterogeneous reservoir under non-pumping or pumping conditions [Jiao & Zhang, 2013]. Unlike the objective-function-based approaches, the inverse method does not require forward flow simulations to assess the data-model misfits; thus the knowledge of reservoir boundary conditions is not needed. The method directly incorporates noisy observed data (i.e., fluid heads, Darcy fluxes, or well rates) at the measurement locations, without solving a boundary value problem. Given sufficient measurement data, it yields well-posed systems of equations that can be solved efficiently with coarse inverse grids and nonlinear optimization. When pumping and injection are active, the well rates can be used as measurements and subsurface flux sampling is not needed. Also, local grid refinement at the well locations is not needed for the inversion to succeed. The method is successfully tested for reservoir problems with regular and irregular geometries, different petrofacies patterns, and permeability anisotropy ratios. All problems yield stable solutions under increasing measurement errors. For a given set of the observation data, inversion accuracy is most affected by the permeability anisotropy ratio. Accuracy in estimating k is also affected by the flow pattern: within a given petrofacies, when the Darcy flux component is extremely small, the corresponding directional permeability perpendicular to streamlines becomes less identifiable. Finally, inversion is successful even if the location of the reservoir boundaries is unknown. In this case, the problem domain for inversion is defined by the location of the measurement data. Select problems are presented below in a set of figures and a table (the relevant quantities have a consistent set of units and are thus not labeled

  12. Nutrient infiltrate concentrations from three permeable pavement types.

    PubMed

    Brown, Robert A; Borst, Michael

    2015-12-01

    While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous asphalt (PA). Each permeable pavement type has four, 54.9-m(2), lined sections that direct all infiltrate into 5.7-m(3) tanks enabling complete volume collection and sampling. This paper highlights the results from a 12-month period when samples were collected from 13 rainfall/runoff events and analyzed for nitrogen species, orthophosphate, and organic carbon. Differences in infiltrate concentrations among the three permeable pavement types were assessed and compared with concentrations in rainwater samples and impervious asphalt runoff samples, which were collected as controls. Contrary to expectations based on the literature, the PA infiltrate had significantly larger total nitrogen (TN) concentrations than runoff and infiltrate from the other two permeable pavement types, indicating that nitrogen leached from materials in the PA strata. There was no significant difference in TN concentration between runoff and infiltrate from either PICP or PC, but TN in runoff was significantly larger than in the rainwater, suggesting meaningful inter-event dry deposition. Similar to other permeable pavement studies, nitrate was the dominant nitrogen species in the infiltrate. The PA infiltrate had significantly larger nitrite and ammonia concentrations than PICP and PC, and this was presumably linked to unexpectedly high pH in the PA infiltrate that greatly exceeded the optimal pH range for nitrifying bacteria. Contrary to the nitrogen results, the PA infiltrate had significantly smaller orthophosphate concentrations than in rainwater, runoff, and infiltrate from PICP

  13. High temperature permeability in volcanic systems: An experimental approach

    NASA Astrophysics Data System (ADS)

    Chadderton, Amy; Sammonds, Peter; Meredith, Philip; Smith, Rosanna; Tuffen, Hugh

    2015-04-01

    The permeability of magma exerts a major influence on volcanic activity and we have long held the ability to experimentally determine the permeability of volcanic material via various techniques. These observations have provided the basis for numerous theories of magmatic degassing. Recent enhancements to the High Temperature Triaxial Deformation Cell (HTTDC) at UCL have enabled us to make permeability measurements on 25mm x 75mm core samples at elevated temperature and elevated hydrostatic pressure (Gaunt et al, 2013). Specifically, we present here the results of several suites of permeability data on samples of dome dacite from Mount St Helens volcano, measured under an effective pressure of 5 MPa (confining pressure of 10 MPa and pore fluid pressure of 5 MPa) and temperatures up to 900oC. Most recently, the capabilities of the HTTDC apparatus have been further extended to enable permeability measurements to be made during triaxial deformation of test samples under similar temperature and pressure conditions. Initial results from this entirely new methodology will also be presented. These new experimental results are being applied to enhance our understanding of the complex issue of silicic magma degassing. Two recent eruptions in Chile, at Chaitén Volcano in 2008-10 and at Cordón Caulle in 2011-12, allowed the first detailed observations of rhyolitic activity and provided previously hidden insights into the evolution of highly silicic eruptions. Both events exhibited simultaneous explosive and effusive activity, with both lava and ash plumes emitted from the same vent (Castro et al, 2014). The permeability of fracture networks that act as fluid flow pathways is key to such eruptive behaviour, and will be investigated systematically at magmatic temperatures and pressures in the presence of pore fluids, using our newly-developed experimental capability. Castro, J.M., Bindeman, I.N., Tuffen, H. and Schipper, I. (2014) EPSL 405, 52-61. Gaunt, H.E., Sammonds, P

  14. 46 CFR 171.072 - Calculation of permeability for Type II subdivision.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Calculation of permeability for Type II subdivision. 171... permeability for Type II subdivision. When doing calcualtions to show compliance with § 171.070, the following uniform average permeabilities must be assumed: (a) 85 percent in the machinery space. (b) 60 percent...

  15. Measuring School Boundary Permeability: The P.S.C.Q. Revised.

    ERIC Educational Resources Information Center

    Wiener, William K.

    This paper discusses the concept of school boundary permeability and describes the field testing and revision of the Parent-School Communities Questionnaire (PSCQ), a survey questionnaire designed to measure the permeability of school boundaries. The concept of permeability assumes that any social system, such as a school, is surrounded by a…

  16. Mitigating methane emissions and air intrusion in heterogeneous landfills with a high permeability layer.

    PubMed

    Jung, Yoojin; Imhoff, Paul T; Augenstein, Don; Yazdani, Ramin

    2011-05-01

    Spatially variable refuse gas permeability and landfill gas (LFG) generation rate, cracking of the soil cover, and reduced refuse gas permeability because of liquid addition can all affect CH(4) collection efficiency when intermediate landfill covers are installed. A new gas collection system that includes a near-surface high permeability layer beneath the landfill cover was evaluated for enhancing capture of LFG and mitigating CH(4) emissions. Simulations of gas transport in two-dimensional domains demonstrated that the permeable layer reduces CH(4) emissions up to a factor of 2 for particular spatially variable gas permeability fields. When individual macrocracks formed in the cover soil and the permeable layer was absent, CH(4) emissions increased to as much as 24% of the total CH(4) generated, double the emissions when the permeable layer was installed. CH(4) oxidation in the cover soil was also much more uniform when the permeable layer was present: local percentages of CH(4) oxidized varied between 94% and 100% across the soil cover with the permeable layer, but ranged from 10% to 100% without this layer for some test cases. However, the permeable layer had a minor effect on CH(4) emissions and CH(4) oxidation in the cover soil when the ratio of the gas permeability of the cover soil to the mean refuse gas permeability ≤ 0.05. The modeling approach employed in this study may be used to assess the utility of other LFG collection systems and management practices.

  17. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  18. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  19. The Permeability of Plant Cell Walls as Measured by Gel Filtration Chromatography

    NASA Astrophysics Data System (ADS)

    Tepeer, Mark; Taylor, Iain E. P.

    1981-08-01

    The permeability of plant cell walls to macromolecules may limit the ability of enzymes to alter the biochemical and physical properties of the wall. Proteins of molecular weight up to 60,000 can permeate a substantial portion of the cell wall. Measurements of wall permeability in which cells are exposed to hypertonic solutions of macromolecules may seriously underestimate wall permeability.

  20. Permeability of Campi Flegrei magmas: examples from the Campanian Ignimbrite and Monte Nuovo eruptions

    NASA Astrophysics Data System (ADS)

    Polacci, Margherita; Bouvet de Maisonneuve, Caroline; Giordano, Daniele; Piochi, Monica; Mancini, Lucia; Degruyter, Wim; Bachmann, Olivier

    2014-05-01

    We performed permeability measurements on trachy-phonolitic pyroclastic products from the Campanian Ignimbrite and Monte Nuovo, two explosive eruptions from the active Campi Flegrei caldera, Southern Italy. Viscous (Darcian) permeability spans a wide range between 1.22x10-14 and 9.31x10-11 m2. Inertial (non-Darcian) permeability follows the same trend as viscous permeability: it increases as viscous permeability increases, highlighting the strong direct correlation between these two parameters. We observe that vesicularity does not exert a first order control on permeability: the Monte Nuovo scoria clasts are the most permeable samples but not the most vesicular; pumice clasts from the Campanian Ignimbrite proximal facies, whose vesicularity is comparable with that of Monte Nuovo scoriae, are instead the least permeable. In addition, we find that sample geometry exhibits permeability anisotropy as samples oriented parallel to vesicle elongation are more permeable than those oriented perpendicular. We compare our results with permeability values of volcanic products from effusive and explosive activity, and discuss the role of melt viscosity and crystallinity on magma permeability.

  1. Tunable negative permeability in a quantum plasmonic metamaterial

    NASA Astrophysics Data System (ADS)

    McEnery, K. R.; Tame, M. S.; Maier, S. A.; Kim, M. S.

    2014-01-01

    We consider the integration of quantum emitters into a negative permeability metamaterial design in order to introduce tunability as well as nonlinear behavior. The unit cell of our metamaterial is a ring of metamolecules, each consisting of a metal nanoparticle and a two-level semiconductor quantum dot (QD). Without the QDs, the ring of the unit cell is known to act as an artificial optical magnetic resonator. By adding the QDs we show that a Fano interference profile is introduced into the magnetic field scattered from the ring. This induced interference is shown to cause an appreciable effect in the collective magnetic resonance of the unit cell. We find that the interference provides a means to tune the response of the negative permeability metamaterial. The exploitation of the QD's inherent nonlinearity is proposed to modulate the metamaterial's magnetic response with a separate control field.

  2. Are extrusive rhyolites produced from permeable foam eruptions?

    NASA Astrophysics Data System (ADS)

    Friedman, I.

    1989-01-01

    The permeable foam hypothesis is suggested by Eichelberger et al. (1986) to explain a major loss of water from rhyolitic magmas in the volcanic conduit. Evidence for the high-water content of the major portion of the magma is herein examined and rejected. Eichelberger's hypothesis does not take into account the large (˜2 orders of magnitude) viscosity change that would occur in the conduit as a result of water loss. It also requires that the permeable foam collapse and weld to form an obsidian that in thin section displays no evidence of the foam. An alternate hypothesis to explain the existence of small amounts of high water content rhyolite glasses in acid volcanoes is that rhyolite magmas are relatively dry (0.1 0.3% H2O) and that water enters the magma from the environment to produce a water-rich selvage which then is kneaded into the body of the magma.

  3. Permittivity and permeability of semi-infinite metamaterial

    NASA Astrophysics Data System (ADS)

    Porvatkina, O. V.; Tishchenko, A. A.; Strikhanov, M. N.

    2016-08-01

    In our work we investigate dielectric and magnetic properties of semi-infinite metamaterial consisting of particles of different possible nature: atoms, molecules, nanoparticles, etc. It is important that these particles would have magnetic properties. Polarization of a near-surface layer is known to differ from its bulk value for non-magnetic materials; for magnetic materials, including metamaterials, the situation should be similar, which is the subject of our research. We obtain analogues of the Clausius-Mossotti relation both for permittivity and permeability taking into account the local field effects in the longwave approximation for semi-infinite metamaterial. These relations describe the connection between macroscopic characteristics of the semi-infinite metamaterial (permittivity and permeability) and characteristics of constituent particles (dielectric polarizability and magnetic polarizability), which is a bright example of multi-scale approach - method very popular today in physical and computer simulating.

  4. Reduction of permeability in granite at elevated temperatures.

    PubMed

    Moore, D E; Lockner, D A; Byerlee, J D

    1994-09-01

    The addition of hydrothermal fluids to heated, intact granite leads to permeability reductions in the temperature range of 300 degrees to 500 degrees C, with the rate of change generally increasing with increasing temperature. The addition of gouge enhances the rate of permeability reduction because of the greater reactivity of the fine material. Flow rate is initially high in a throughgoing fracture but eventually drops to the level of intact granite. These results support the fault-valve model for the development of mesothermal ore deposits, in which seals are formed at the base of the seismogenic zone of high-angle thrust faults. The lower temperature results yield varying estimates of mineral-sealing rates at shallower depths in fault zones, although they generally support the hypothesis that such seals develop in less time than the recurrence interval for moderate to large earthquakes on the San Andreas fault.

  5. Reduction of permeability in granite at elevated temperatures

    USGS Publications Warehouse

    Moore, Diane E.; Lockner, D.A.; Byerlee, J.D.

    1994-01-01

    The addition of hydrothermal fluids to heated, intact granite leads to permeability reductions in the temperature range of 300?? to 500??C, with the rate of change generally increasing with increasing temperature. The addition of gouge enhances the rate of permeability reduction because of the greater reactivity of the fine material. Flow rate is initially high in a throughgoing fracture but eventually drops to the level of intact granite. These results support the fault-valve model for the development of mesothermal ore deposits, in which seals are formed at the base of the seismogenic zone of high-angle thrust faults. The lower temperature results yield varying estimates of mineral-sealing rates at shallower depths in fault zones, although they generally support the hypothesis that such seals develop in less time than the recurrence interval for moderate to large earthquakes on the San Andreas fault.

  6. Probing nanoparticle translocation across the permeable endothelium in experimental atherosclerosis.

    PubMed

    Kim, Yongtae; Lobatto, Mark E; Kawahara, Tomohiro; Lee Chung, Bomy; Mieszawska, Aneta J; Sanchez-Gaytan, Brenda L; Fay, Francois; Senders, Max L; Calcagno, Claudia; Becraft, Jacob; Tun Saung, May; Gordon, Ronald E; Stroes, Erik S G; Ma, Mingming; Farokhzad, Omid C; Fayad, Zahi A; Mulder, Willem J M; Langer, Robert

    2014-01-21

    Therapeutic and diagnostic nanomaterials are being intensely studied for several diseases, including cancer and atherosclerosis. However, the exact mechanism by which nanomedicines accumulate at targeted sites remains a topic of investigation, especially in the context of atherosclerotic disease. Models to accurately predict transvascular permeation of nanomedicines are needed to aid in design optimization. Here we show that an endothelialized microchip with controllable permeability can be used to probe nanoparticle translocation across an endothelial cell layer. To validate our in vitro model, we studied nanoparticle translocation in an in vivo rabbit model of atherosclerosis using a variety of preclinical and clinical imaging methods. Our results reveal that the translocation of lipid-polymer hybrid nanoparticles across the atherosclerotic endothelium is dependent on microvascular permeability. These results were mimicked with our microfluidic chip, demonstrating the potential utility of the model system.

  7. Structural permeability of complex networks to control signals

    NASA Astrophysics Data System (ADS)

    Lo Iudice, Francesco; Garofalo, Franco; Sorrentino, Francesco

    2015-09-01

    Many biological, social and technological systems can be described as complex networks. The goal of affecting their behaviour has motivated recent work focusing on the relationship between the network structure and its propensity to be controlled. While this work has provided insight into several relevant problems, a comprehensive approach to address partial and complete controllability of networks is still lacking. Here, we bridge this gap by developing a framework to maximize the diffusion of the control signals through a network, while taking into account physical and economic constraints that inevitably arise in applications. This approach allows us to introduce the network permeability, a unified metric of the propensity of a network to be controllable. The analysis of the permeability of several synthetic and real networks enables us to extract some structural features that deepen our quantitative understanding of the ease with which specific controllability requirements can be met.

  8. Thermal treatment of low permeability soils using electrical resistance heating

    SciTech Connect

    Udell, K.S.

    1996-08-01

    The acceleration of recovery rates of second phase liquid contaminants from the subsurface during gas or water pumping operations is realized by increasing the soil and ground water temperature. Electrical heating with AC current is one method of increasing the soil and groundwater temperature and has particular applicability to low permeability soils. Several mechanisms have been identified that account for the enhanced removal of the contaminants during electrical heating. These are vaporization of liquid contaminants with low boiling points, temperature-enhanced evaporation rates of semi-volatile components, and removal of residual contaminants by the boiling of residual water. Field scale studies of electrical heating and fluid extraction show the effectiveness of this technique and its applicability to contaminants found both above and below the water table and within low permeability soils. 10 refs., 8 figs.

  9. Influence of wall permeability on turbulent boundary-layer properties

    NASA Technical Reports Server (NTRS)

    Wilkinson, S. P.

    1983-01-01

    Experimental boundary-layer studies of a series of low pressure drop, permeable surfaces have been conducted to characterize their surface interaction with a turbulent boundary layer. The models were flat and tested at nominally zero pressure gradient in low speed air. The surfaces were thin metal sheets with discrete perforations. Direct drag balance measurements of skin friction indicate that the general effect of surface permeability is to increase drag above that of a smooth plate reference level. Heuristic arguments are presented to show that this type of behavior is to be expected. Other boundary-layer data are also presented including mean velocity profiles and conditionally sampled streamwise velocity fluctuations (hot wire) for selected models.

  10. Mitochondrial Permeability Transition: New Findings and Persisting Uncertainties.

    PubMed

    Izzo, Valentina; Bravo-San Pedro, José Manuel; Sica, Valentina; Kroemer, Guido; Galluzzi, Lorenzo

    2016-09-01

    Several insults cause the inner mitochondrial membrane to abruptly lose osmotic homeostasis, hence initiating a regulated variant of cell death known as 'mitochondrial permeability transition' (MPT)-driven necrosis. MPT provides an etiological contribution to several human disorders characterized by the acute loss of post-mitotic cells, including cardiac and cerebral ischemia. Nevertheless, the precise molecular determinants of MPT remain elusive, which considerably hampers the development of clinically implementable cardio- or neuroprotective strategies targeting this process. We summarize recent findings shedding new light on the supramolecular entity that mediates MPT, the so-called 'permeability transition pore complex' (PTPC). Moreover, we discuss hitherto unresolved controversies on MPT and analyze the major obstacles that still preclude the complete understanding and therapeutic targeting of this process.

  11. Spontaneous Imbibition in Low Permeability Medium, SUPRI TR-114

    SciTech Connect

    Kovscek, Anthony R.; Schembre, Josephina

    1999-08-09

    A systematic experimental investigation of capillary pressure characteristics and fluid flow in diatomite was begun. Using an X-ray CT scanner and a specially constructed imbibition cell, we study spontaneous water imbibition processes in diatomite and, for reference, Berea sandstone and chalk. The mass of water imbibed as a function of time is also measured. Imbibition is restricted to concurrent flow. Despite a marked difference in rock properties such as permeability and porosity, we find similar trends in saturation profiles and weight gain versus time functions. Imbibition in diatomote is relatively rapid when initial water saturation is low due to large capillary forces. Using a non-linear regression analysis together with the experimental data, the capillary pressure and water relative permeability curves are determined for the diatomite in the water-air system. The results given for displacement profiles by numerical simulation match the experimental results.

  12. Effect of drying on viscoelasticity and permeability of gel

    SciTech Connect

    Scherer, G.W.

    1994-12-31

    The beam-bending method was used to measure the effect of partial drying on the viscoelastic relaxation behavior and permeability of a two-step acid-base catalyzed silica gel. Both the elastic modulus (E) and the permeability (D) showed a power-law dependence on density ({rho}): E {approximately} {rho}{sup m} {approx} 3.0; D {approximately} {rho}{sup {minus}n}, n {approx} 2.5. The viscosity of the network rose from {approximately}10{sup 11} to {approximately}10{sup 13} Pa{center_dot}s, and was strongly dependent on age as well as density of the gel. The viscoelastic relaxation function was well described by the stretched exponential function with an exponent of 0.3--0.5.

  13. Novel JAK1-selective benzimidazole inhibitors with enhanced membrane permeability.

    PubMed

    Kim, Hyungmi; Kim, Mi Kyoung; Choo, Hyunah; Chong, Youhoon

    2016-07-15

    The previously identified Janus kinase 1 (JAK1)-selective inhibitor, 1-(2-aminoethyl)-2-(piperidin-4-yl)-1H-benzo[d]imidazole-5-carboxamide (2), suffered from low cell permeability, which resulted in poor pharmacokinetic properties. In this study, by introducing less polar hydrogen bond donors at N(1) (a hydroxyalkyl or a methylaminoalkyl group) and C2 (a cyclohexanol group) positions, a series of novel benzimidazole derivatives were prepared, which exhibited selective JAK1 inhibitory activity (IC50 against JAK1=0.08-0.15μM; JAK1-selectivity=26-40 fold vs JAK2, 12-23 fold vs JAK3, and 38-54 fold vs Tyk2) along with significantly increased lipophilicity (3.3-15.8 times) as well as membrane permeability (6.3-12 times). PMID:27261178

  14. Biopolymer system for permeability modification in porous media

    SciTech Connect

    Stepp, A.K.; Bryant, R.S.; Llave, F.M.

    1995-12-31

    New technologies are needed to reduce the current high rate of well abandonment. Improved sweep efficiency, reservoir conformance, and permeability modification can have a significant impact on oil recovery processes. Microorganisms can be used to selectively plug high-permeability zones to improve sweep efficiency and impart conformance control. Studies of a promising microbial system for polymer production were conducted to evaluate reservoir conditions in which this system would be effective. Factors which can affect microbial growth and polymer production include salinity, pH, temperature, divalent ions, presence of residual oil, and rock matrix. Flask tests and coreflooding experiments were conducted to optimize and evaluate the effectiveness of this system. Nuclear magnetic resonance imaging (NMRI) was used to visualize microbial polymer production in porous media. Changes in fluid distribution within the pore system of the core were detected.

  15. Are extrusive rhyolites produced from permeable foam eruptions?

    USGS Publications Warehouse

    Friedman, I.

    1989-01-01

    The permeable foam hypothesis is suggested by Eichelberger el al. (1986) to explain a major loss of water from rhyolithic magmas in the volcanic conduit. Evidence for the high-water content of the major portion of the magmas is herein examined and rejected. Eichelberger's hypothesis does not take into account the large (~2 orders of magnitude) viscosity change that would occur in the conduit as a result of water loss. It also requires that the permeable foam collapse and weld to form an obsidian that in thin section displays no evidence of the foam. An alternate hypothesis to explain the existence of small amounts of high water content rhyolite glasses in acid volcanoes is that rhyolite magmas are relatively dry (0.1-0.3% H2O) and that water enters the magma from the environment to produce a water-rich selvage which then is kneaded into the body of the magma. -Author

  16. Increased bladder permeability in interstitial cystitis/painful bladder syndrome

    PubMed Central

    Greenwood-Van Meerveld, Beverley; Wisniewski, Amy B.; VanGordon, Samuel; Lin, HsuehKung; Kropp, Bradley P.; Towner, Rheal A.

    2015-01-01

    The definition of interstitial cystitis (IC) has evolved over the years from being a well-defined entity characterized by diagnostic lesion (Hunner’s ulcer) in the urothelium to a clinical diagnosis by exclusion [painful bladder syndrome (PBS)]. Although the etiology is unknown, a central theme has been an association with increased permeability of the bladder. This article reviews the evidence for increased permeability being important to the symptoms of interstitial cystitis/painful bladder syndrome (IC/PBS) and in treating the disorder. Recent work showing cross-communication among visceral organs is also reviewed to provide a basis for understanding IC/PBS as a systemic disorder of a complex, interconnected system consisting of the bladder, bowel and other organs, nerves, cytokine-responding cells and the nervous system. PMID:26751576

  17. Tubular hydrogen permeable metal foil membrane and method of fabrication

    DOEpatents

    Paglieri, Stephen N.; Birdsell, Stephen A.; Barbero, Robert S.; Snow, Ronny C.; Smith, Frank M.

    2006-04-04

    A tubular hydrogen permeable metal membrane and fabrication process comprises obtaining a metal alloy foil having two surfaces, coating the surfaces with a metal or metal alloy catalytic layer to produce a hydrogen permeable metal membrane, sizing the membrane into a sheet with two long edges, wrapping the membrane around an elongated expandable rod with the two long edges aligned and overlapping to facilitate welding of the two together, placing the foil wrapped rod into a surrounding fixture housing with the two aligned and overlapping foil edges accessible through an elongated aperture in the surrounding fixture housing, expanding the elongated expandable rod within the surrounding fixture housing to tighten the foil about the expanded rod, welding the two long overlapping foil edges to one another generating a tubular membrane, and removing the tubular membrane from within the surrounding fixture housing and the expandable rod from with the tubular membrane.

  18. Simultaneous estimation of relative permeabilities and capillary pressure

    SciTech Connect

    Chardaire-Riviere, C.; Bourbiaux, B.J. , 92 - Rueil-Malmaison ); Chavent, G.; Jaffre, J.; Liu, J. )

    1992-12-01

    In this paper, an automatic numerical method is proposed for simultaneous determination of relative permeabilities and capillary pressure from the results of a single two-phase flow experiment in a range of velocities representative of field flow conditions. The experiment is a standard imbibition or drainage displacement with an imposed difference of pressure or flow rate. The experimental data used are the outlet production, the pressure drop between the two faces, and local saturation profiles at different times along the core. Relative permeabilities and capillary pressure are estimated with a least-square technique. Use of a high-order numerical scheme significantly reduces the numerical diffusion. The optimal control theory is used to solve the minimization problem. The corresponding FORTRAN code is generated by a symbolic program. The validity of the method first is demonstrated with simulated data, then is tested in tow laboratory experiments: one imbibition and one drainage. Good agreement is obtained for both situations.

  19. Hydrogen Permeability of Polymer Matrix Composites at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Grenoble, Ray W.; Gates, Thomas S

    2005-01-01

    This paper presents experimental methods and results of an ongoing study of the correlation between damage state and hydrogen gas permeability of laminated composite materials under mechanical strains and thermal loads. A specimen made from IM-7/977-2 composite material has been mechanically cycled at room temperature to induce microcrack damage. Crack density and tensile modulus were observed as functions of number of cycles. Damage development was found to occur most quickly in the off-axis plies near the outside of the laminate. Permeability measurements were made after 170,000 cycles and 430,000 cycles. Leak rate was found to depend on applied mechanical strain, crack density, and test temperature.

  20. Diffusional water permeability of mammalian red blood cells.

    PubMed

    Benga, G; Borza, T

    1995-12-01

    An extensive programme of comparative nuclear magnetic resonance measurements of the membrane diffusional permeability for water (Pd) and of the activation energy (Ea,d) of this process in red blood cells (RBCs) from 21 mammalian species was carried out. On the basis of Pd, these species could be divided into three groups. First, the RBC's from humans, cow, sheep and "large" kangaroos (Macropus giganteus and Macropus rufus) had Pd values approximately 5 x 10(-3) cm/s at 25 degrees and 7 x 10(-3) cm/s at 37 degrees C. The RBCs from other marsupial species, mouse, rat, guinea pig and rabbit, had Pd values roughly twice higher, whereas echidna RBCs were twice lower than human RBCs. The value of Ea,d was in most cases correlated with the values of Pd. A value of Ea,d approximately 26 kJ/mol was found for the RBCs from humans and the species having similar Pd values. Low values of Ea,d (ranging from 15 to 22 kJ/mol) appeared to be associated with relatively high values of Pd. The highest values of Ea,d (33 kJ/mol) was found in echidna RBCs. This points to specialized channels for water diffusion incorporated in membrane proteins; a relatively high water permeability of the RBC membrane could be due to a greater number of channel proteins. There are, however, situations where a very high water permeability of RBCs is associated with a high value of Ea,d (above 25 kJ/mol) as in the case of RBCs from mouse, rat and tree kangaroo. Moreover, it was found that Pd in different species was positively correlated to the RBC membrane phosphatidylcholine and negatively correlated to the sphingomyelin content. This suggests that in addition to the number of channel proteins, other factors are involved in the water permeability of the RBC membrane.

  1. Pneumatic permeability measurements in a fractured, partially saturated environment

    SciTech Connect

    Guzman, A.; Sully, M.; Neuman, S.; Lohrstorfer, C.

    1993-06-01

    In the context of underground disposal of high-level radioactive wastes, the hydraulic conductivity of the host environment is an extremely important parameter. The research task of the authors addresses the technical design of instrumentation and the theoretical aspects of air flow through fractured, unsaturated rocks. Determinations of the pneumatic permeability are being conducted at different scales in selected boreholes located in unsaturated tuff at the Apache Leap Tuff site. 1 fig.

  2. Depth-weighted, mean soil permeability in Kansas

    USGS Publications Warehouse

    Juracek, Kyle E.

    2000-01-01

    This digital spatial data set provides information on the magnitude and spatial pattern of depth-weighted, mean soil permeability throughout the State of Kansas. The data set was assembled using 1:24,000-scale cartographic and attribute information on the spatial distribution and characteristics of Kansas soils. The data set is in grid (raster) format with a grid-cell size of 10,000 square meters.

  3. Photoresponsive vesicle permeability based on intramolecular host-guest inclusion.

    PubMed

    Kauscher, Ulrike; Samanta, Avik; Ravoo, Bart Jan

    2014-01-28

    This article describes light-responsive vesicles that can release their contents in response to a light-sensitive molecular trigger. To this end, liposomes were equipped with amphiphilic β-cyclodextrin that was covalently labeled with azobenzene. Using dye encapsulation and confocal laser scanning microscopy, we show that the permeability of these vesicles strongly increases upon UV irradiation (λ = 350 nm) with concomitant isomerization of apolar trans-azobenzene to polar cis-azobenzene on the liposome surface. PMID:24287588

  4. Evaluation of dentin permeability after light activated internal dental bleaching.

    PubMed

    Carrasco, Laise Daniela; Zanello Guerisoli, Danilo M; Pécora, Jesus Djalma; Fröner, Izabel Cristina

    2007-02-01

    The aim of this in vitro study was to assess quantitatively the dentin permeability of human teeth after intracoronal bleaching therapy with 35% hydrogen peroxide activated by LEDs, halogen lamp or using the walking bleach technique. Forty human maxillary central incisors had standard access cavities performed and the cervical thirds of the canals were prepared with Gates-Glidden drills up to a size 130. Roots were resected between the coronal and middle thirds and the apical portions were discarded. A glass ionomer, 2 mm thick cervical plug was placed inside the canal, at the cement-enamel junction level. Group I received 35% hydrogen peroxide gel activated by LEDs. Group II was submitted to 35% hydrogen peroxide gel activated by halogen lamp. Group III received 35% hydrogen peroxide gel and the walking bleach technique was followed. Group IV (control) received a dry cotton pellet inside the pulp chamber with temporary restoration. Dentinal permeability was quantified by copper ion penetration. Linear measurements were obtained by analysis of digital images under x 5 magnification. Mean values and SD for the experimental groups were: I, 7.1% (+/-3.2%); II, 8.4% (+/-3.0%); III, 9.1% (+/-3.0%); IV, 1.3% (+/-2.8%). One-way ANOVA was used to analyze the results. Results showed an increase of permeability values for groups I, II and III when compared to group IV (control); however, no statistical differences were found between the three tested bleaching techniques. It can be concluded that 35% hydrogen peroxide activated by LED, halogen lamp or used following the walking bleach technique produced similar increase in dentinal permeability. PMID:17227378

  5. Test device for measuring permeability of a barrier material

    SciTech Connect

    Reese, Matthew; Dameron, Arrelaine; Kempe, Michael

    2014-03-04

    A test device for measuring permeability of a barrier material. An exemplary device comprises a test card having a thin-film conductor-pattern formed thereon and an edge seal which seals the test card to the barrier material. Another exemplary embodiment is an electrical calcium test device comprising: a test card an impermeable spacer, an edge seal which seals the test card to the spacer and an edge seal which seals the spacer to the barrier material.

  6. Water and nonelectrolyte permeability of isolated rat hepatocytes

    SciTech Connect

    Alpini, G.; Garrick, R.A.; Jones, M.J.; Nunes, R.; Tavoloni, N.

    1986-12-01

    We have measured the diffusive permeability coefficients of isolated rat hepatocytes to /sup 3/H/sub 2/O, (/sup 14/C)urea, (/sup 14/C)erythritol, (/sup 14/C)mannitol, (/sup 3/H)sucrose, and (/sup 3/H)inulin, employing a technique previously developed for erythrocytes (Redwood et al., J. Gen. Physiol 64:706-729, 1974). Diffusion coefficients for the tracer molecules were measured in packed hepatocytes, supernatant fluid, and intracellular medium (lysed hepatocytes) and were calculated assuming one-dimensional semi-infinite diffusion through a homogeneous medium. By applying the series-parallel pathway model, the following permeability coefficients (10(-5) cm/sec) for the hepatocyte plasma membrane were obtained. /sup 3/H/sub 2/O, 98.6 +/- 18.4; (/sup 14/C)urea, 18.2 +/- 5.3; (/sup 14/C)erythritol, 4.8 +/- 1.6; (/sup 14/C)mannitol, 3.1 +/- 1.4; (/sup 3/H)sucrose, 0; (/sup 3/H)inulin, 0. These results indicate that isolated rat hepatocytes are highly permeable to water and polar nonelectrolytes, when compared with other transporting epithelia. This relatively high cellular permeability is consistent with a model in which nonelectrolyte permeation is via an aqueous pathway of equivalent pore diameter of 8-12 A. The finding that (/sup 14/C)erythritol and (/sup 14/C)mannitol cross the hepatocyte plasma membrane indicates that these molecules enter the bile canaliculus through the transcellular route. Conversely, the failure of (/sup 3/H)sucrose and (/sup 3/H)inulin to permeate the hepatocyte in the isolated condition supports the concept that biliary entry of these large carbohydrates, at least that fraction which cannot be accounted for by a vesicular mechanism, must occur via the transjunctional shunt pathway.

  7. Tumor vascular permeability factor stimulates endothelial cell growth and angiogenesis.

    PubMed Central

    Connolly, D T; Heuvelman, D M; Nelson, R; Olander, J V; Eppley, B L; Delfino, J J; Siegel, N R; Leimgruber, R M; Feder, J

    1989-01-01

    Vascular permeability factor (VPF) is an Mr 40-kD protein that has been purified from the conditioned medium of guinea pig line 10 tumor cells grown in vitro, and increases fluid permeability from blood vessels when injected intradermally. Addition of VPF to cultures of vascular endothelial cells in vitro unexpectedly stimulated cellular proliferation. VPF promoted the growth of new blood vessels when administered into healing rabbit bone grafts or rat corneas. The identity of the growth factor activity with VPF was established in four ways: (a) the molecular weight of the activity in preparative SDS-PAGE was the same as VPF (Mr approximately 40 kD); (b) multiple isoforms (pI greater than or equal to 8) for both VPF and the growth-promoting activity were observed; (c) a single, unique NH2-terminal amino acid sequence was obtained; (d) both growth factor and permeability-enhancing activities were immunoadsorbed using antipeptide IgG that recognized the amino terminus of VPF. Furthermore, 125I-VPF was shown to bind specifically and with high affinity to endothelial cells in vitro and could be chemically cross-linked to a high-molecular weight cell surface receptor, thus demonstrating a mechanism whereby VPF can interact directly with endothelial cells. Unlike other endothelial cell growth factors, VPF did not stimulate [3H]thymidine incorporation or promote growth of other cell types including mouse 3T3 fibroblasts or bovine smooth muscle cells. VPF, therefore, appears to be unique in its ability to specifically promote increased vascular permeability, endothelial cell growth, and angio-genesis. Images PMID:2478587

  8. A Collection of Complex Permittivity and Permeability Measurements

    SciTech Connect

    Barry, W.; Byrd, J.; Johnson, J.; Smithwick, J.

    1993-02-01

    We present the results of measurements of the complex permittivity and permeability over a frequency range of 0.1-5.1 GHz for a range of microwave absorbing materials used in a variety of accelerator applications. We also describe the automated measurement technique which uses swept-frequency S-parameter measurements made on a strip transmission line device loaded with the material under test.

  9. Vascular permeability in a human tumour xenograft: molecular charge dependence

    PubMed Central

    Dellian, M; Yuan, F; Trubetskoy, V S; Torchilin, V P; Jain, R K

    2000-01-01

    Molecular charge is one of the main determinants of transvascular transport. There are, however, no data available on the effect of molecular charge on microvascular permeability of macromolecules in solid tumours. To this end, we measured tumour microvascular permeability to different proteins having similar size but different charge. Measurements were performed in the human colon adenocarcinoma LS174T transplanted in transparent dorsal skinfold chambers in severe combined immunodeficient (SCID) mice. Bovine serum albumin (BSA) and IgG were fluorescently labelled and were either cationized by conjugation with hexamethylenediamine or anionized by succinylation. The molecules were injected i.v. and the fluorescence in tumour tissue was quantified by intravital fluorescence microscopy. The fluorescence intensity and pharmacokinetic data were used to calculate the microvascular permeability. We found that tumour vascular permeability of cationized BSA (pI-range: 8.6–9.1) and IgG (pI: 8.6–9.3) was more than two-fold higher (4.25 and 4.65 × 10−7cm s−1) than that of the anionized BSA (pI ≈ 2.0) and IgG (pI: 3.0–3.9; 1.11 and 1.93 × 10−7cm s−1, respectively). Our results indicate that positively charged molecules extravasate faster in solid tumours compared to the similar-sized compounds with neutral or negative charges. However, the plasma clearance of cationic molecules was ∼2 × faster than that of anionic ones, indicating that the modification of proteins enhances drug delivery to normal organs as well. Therefore, caution should be exercised when such a strategy is used to improve drug and gene delivery to solid tumours. © 2000 Cancer Research Campaign PMID:10789717

  10. Vascular permeability in a human tumour xenograft: molecular charge dependence.

    PubMed

    Dellian, M; Yuan, F; Trubetskoy, V S; Torchilin, V P; Jain, R K

    2000-05-01

    Molecular charge is one of the main determinants of transvascular transport. There are, however, no data available on the effect of molecular charge on microvascular permeability of macromolecules in solid tumours. To this end, we measured tumour microvascular permeability to different proteins having similar size but different charge. Measurements were performed in the human colon adenocarcinoma LS174T transplanted in transparent dorsal skinfold chambers in severe combined immunodeficient (SCID) mice. Bovine serum albumin (BSA) and IgG were fluorescently labelled and were either cationized by conjugation with hexamethylenediamine or anionized by succinylation. The molecules were injected i.v. and the fluorescence in tumour tissue was quantified by intravital fluorescence microscopy. The fluorescence intensity and pharmacokinetic data were used to calculate the microvascular permeability. We found that tumour vascular permeability of cationized BSA (pI-range: 8.6-9.1) and IgG (pI: 8.6-9.3) was more than two-fold higher (4.25 and 4.65x10(-7) cm s(-1)) than that of the anionized BSA (pI approximately 2.0) and IgG (pI: 3.0-3.9; 1.11 and 1.93x10(-7) cm s(-1), respectively). Our results indicate that positively charged molecules extravasate faster in solid tumours compared to the similar-sized compounds with neutral or negative charges. However, the plasma clearance of cationic molecules was approximately 2x faster than that of anionic ones, indicating that the modification of proteins enhances drug delivery to normal organs as well. Therefore, caution should be exercised when such a strategy is used to improve drug and gene delivery to solid tumours.

  11. Use of Interface Treatment to Reduce Emissions from Residuals in Lower Permeability Zones to Groundwater flowing Through More Permeable Zones (Invited)

    NASA Astrophysics Data System (ADS)

    Johnson, P.; Cavanagh, B.; Clifton, L.; Daniels, E.; Dahlen, P.

    2013-12-01

    Many soil and groundwater remediation technologies rely on fluid flow for contaminant extraction or reactant delivery (e.g., soil vapor extraction, pump and treat, in situ chemical oxidation, air sparging, enhanced bioremediation). Given that most unconsolidated and consolidated settings have permeability contrasts, the outcome is often preferential treatment of more permeable zones and ineffective treatment of the lower permeability zones. When this happens, post-treatment contaminant emissions from low permeability zone residuals can cause unacceptable long-term impacts to groundwater in the transmissive zones. As complete remediation of the impacted lower permeability zones may not be practicable with conventional technologies, one might explore options that lead to reduction of the contaminant emissions to acceptable levels, rather than full remediation of the lower permeability layers. This could be accomplished either by creating a sustained emission reaction/attenuation zone at the high-low permeability interface, or by creating a clean soil zone extending sufficiently far into the lower permeability layer to cause the necessary reduction in contaminant concentration gradient and diffusive emission. These options are explored in proof-of-concept laboratory-scale physical model experiments. The physical models are prepared with two layers of contrasting permeability and either dissolved matrix storage or nonaqueous phase liquid (NAPL) in the lower permeability layer. A dissolved oxidant is then delivered to the interface via flow across the higher permeability layer and changes in contaminant emissions from the low permeability zone are monitored before, during, and after oxidant delivery. The use of three oxidants (dissolved oxygen, hydrogen peroxide and sodium persulfate) for treatment of emissions from petroleum hydrocarbon residuals is examined.

  12. Red Cell Membrane Permeability Deduced from Bulk Diffusion Coefficients

    PubMed Central

    Redwood, W. R.; Rall, E.; Perl, W.

    1974-01-01

    The permeability coefficients of dog red cell membrane to tritiated water and to a series of[14C]amides have been deduced from bulk diffusion measurements through a "tissue" composed of packed red cells. Red cells were packed by centrifugation inside polyethylene tubing. The red cell column was pulsed at one end with radiolabeled solute and diffusion was allowed to proceed for several hours. The distribution of radioactivity along the red cell column was measured by sequential slicing and counting, and the diffusion coefficient was determined by a simple plotting technique, assuming a one-dimensional diffusional model. In order to derive the red cell membrane permeability coefficient from the bulk diffusion coefficient, the red cells were assumed to be packed in a regular manner approximating closely spaced parallelopipeds. The local steady-state diffusional flux was idealized as a one-dimensional intracellular pathway in parallel with a one-dimensional extracellular pathway with solute exchange occurring within the series pathway and between the pathways. The diffusion coefficients in the intracellular and extracellular pathways were estimated from bulk diffusion measurements through concentrated hemoglobin solutions and plasma, respectively; while the volume of the extracellular pathway was determined using radiolabeled sucrose. The membrane permeability coefficients were in satisfactory agreement with the data of Sha'afi, R. I., C. M. Gary-Bobo, and A. K. Solomon (1971. J. Gen. Physiol. 58:238) obtained by a rapid-reaction technique. The method is simple and particularly well suited for rapidly permeating solutes. PMID:4443795

  13. Modulation of muscle contraction by a cell-permeable peptide

    PubMed Central

    Tünnemann, Gisela; Karczewski, Peter; Haase, Hannelore

    2007-01-01

    In contrast to immortal cell lines, primary cells are hardly susceptible to intracellular delivery methods such as transfection. In this study, we evaluated the direct delivery of several cell-permeable peptides under noninvasive conditions into living primary adult rat cardiomyocytes. We specifically monitored the functional effects of a cell-permeable peptide containing the 15 amino acid N-terminal peptide from human ventricular light chain-1 (VLC-1) on contraction and intracellular Ca2+ signals after electrical stimulation in primary adult cardiomyocytes. The transducible VLC-1 variant was taken up by cardiomyocytes within 5 min with more than 95% efficiency and localized to sarcomeric structures. Analysis of the functional effects of the cell-permeable VLC-1 revealed an enhancement of the intrinsic contractility of cardiomyocytes without affecting the intracellular Ca2+. Therefore, peptide transduction mediated by cell-penetrating peptides represents not only a unique strategy to enhance heart muscle function with no secondary effect on intracellular Ca2+ but also an invaluable tool for the modulation and manipulation of protein interactions in general and in primary cells. PMID:17717642

  14. A Microscopic Multiphase Diffusion Model of Viable Epidermis Permeability

    PubMed Central

    Nitsche, Johannes M.; Kasting, Gerald B.

    2013-01-01

    A microscopic model of passive transverse mass transport of small solutes in the viable epidermal layer of human skin is formulated on the basis of a hexagonal array of cells (i.e., keratinocytes) bounded by 4-nm-thick, anisotropic lipid bilayers and separated by 1-μm layers of extracellular fluid. Gap junctions and tight junctions with adjustable permeabilities are included to modulate the transport of solutes with low membrane permeabilities. Two keratinocyte aspect ratios are considered to represent basal and spinous cells (longer) and granular cells (more flattened). The diffusion problem is solved in a unit cell using a coordinate system conforming to the hexagonal cross section, and an efficient two-dimensional treatment is applied to describe transport in both the cell membranes and intercellular spaces, given their thinness. Results are presented in terms of an effective diffusion coefficient, D¯epi, and partition coefficient, K¯epi/w, for a homogenized representation of the microtransport problem. Representative calculations are carried out for three small solutes—water, L-glucose, and hydrocortisone—covering a wide range of membrane permeability. The effective transport parameters and their microscopic interpretation can be employed within the context of existing three-layer models of skin transport to provide more realistic estimates of the epidermal concentrations of topically applied solutes. PMID:23708370

  15. Computation of streaming potential in porous media: Modified permeability tensor

    NASA Astrophysics Data System (ADS)

    Bandopadhyay, Aditya; DasGupta, Debabrata; Mitra, Sushanta K.; Chakraborty, Suman

    2015-11-01

    We quantify the pressure-driven electrokinetic transport of electrolytes in porous media through a matched asymptotic expansion based method to obtain a homogenized description of the upscaled transport. The pressure driven flow of aqueous electrolytes over charged surfaces leads to the generation of an induced electric potential, commonly termed as the streaming potential. We derive an expression for the modified permeability tensor, K↔eff, which is analogous to the Darcy permeability tensor with due accounting for the induced streaming potential. The porous media herein are modeled as spatially periodic. The modified permeability tensor is obtained for both topographically simple and complex domains by enforcing a zero net global current. Towards resolving the complicated details of the porous medium in a computationally efficient framework, the domain identification and reconstruction of the geometries are performed using adaptive quadtree (in 2D) and octree (in 3D) algorithms, which allows one to resolve the solid-liquid interface as per the desired level of resolution. We discuss the influence of the induced streaming potential on the modification of the Darcy law in connection to transport processes through porous plugs, clays and soils by considering a case-study on Berea sandstone.

  16. Permeability of Two Parachute Fabrics - Measurements, Modeling, and Application

    NASA Technical Reports Server (NTRS)

    Cruz, Juan R.; O'Farrell, Clara; Hennings, Elsa; Runnells, Paul

    2016-01-01

    Two parachute fabrics, described by Parachute Industry Specifications PIA-C-7020D Type I and PIA-C-44378D Type I, were tested to obtain their permeabilities in air (i.e., flow-through volume of air per area per time) over the range of differential pressures from 0.146 psf (7 Pa) to 25 psf (1197 Pa). Both fabrics met their specification permeabilities at the standard differential pressure of 0.5 inch of water (2.60 psf, 124 Pa). The permeability results were transformed into an effective porosity for use in calculations related to parachutes. Models were created that related the effective porosity to the unit Reynolds number for each of the fabrics. As an application example, these models were used to calculate the total porosities for two geometrically-equivalent subscale Disk-Gap-Band (DGB) parachutes fabricated from each of the two fabrics, and tested at the same operating conditions in a wind tunnel. Using the calculated total porosities and the results of the wind tunnel tests, the drag coefficient of a geometrically-equivalent full-scale DGB operating on Mars was estimated.

  17. Microfluidic Fabrication of Pluronic Vesicles with Controlled Permeability.

    PubMed

    do Nascimento, Débora F; Arriaga, Laura R; Eggersdorfer, Max; Ziblat, Roy; Marques, Maria de Fátima V; Reynaud, Franceline; Koehler, Stephan A; Weitz, David A

    2016-05-31

    Block copolymers with a low hydrophilic-to-lipophilic balance form membranes that are highly permeable to hydrophilic molecules. Polymersomes with this type of membrane enable the controllable release of molecules without membrane rupture. However, these polymersomes are difficult to assemble because of their low hydrophobicity. Here, we report a microfluidic approach to the production of these polymersomes using double-emulsion drops with ultrathin shells as templates. The small thickness of the middle oil phase enables the attraction of the hydrophobic blocks of the polymers adsorbed at each of the oil/water interfaces of the double emulsions; this results in the dewetting of the oil from the surface of the innermost water drops of the double emulsions and the ultimate formation of the polymersome. This approach to polymersome fabrication enables control of the vesicle size and results in the efficient encapsulation of hydrophilic ingredients that can be released through the polymer membrane without membrane rupture. We apply our approach to the fabrication of Pluronic L121 vesicles and characterize the permeability of their membranes. Furthermore, we show that membrane permeability can be tuned by blending different Pluronic polymers. Our work thus describes a route to producing Pluronic vesicles that are useful for the controlled release of hydrophilic ingredients. PMID:27192611

  18. Sensitivity analysis of permeability parameters for flows on Barcelona networks

    NASA Astrophysics Data System (ADS)

    Rarità, Luigi; D'Apice, Ciro; Piccoli, Benedetto; Helbing, Dirk

    We consider the problem of optimizing vehicular traffic flows on an urban network of Barcelona type, i.e. square network with streets of not equal length. In particular, we describe the effects of variation of permeability parameters, that indicate the amount of flow allowed to enter a junction from incoming roads. On each road, a model suggested by Helbing et al. (2007) [11] is considered: free and congested regimes are distinguished, characterized by an arrival flow and a departure flow, the latter depending on a permeability parameter. Moreover we provide a rigorous derivation of the model from fluid dynamic ones, using recent results of Bretti et al. (2006) [3]. For solving the dynamics at nodes of the network, a Riemann solver maximizing the through flux is used, see Coclite et al. (2005) [4] and Helbing et al. (2007) [11]. The network dynamics gives rise to complicate equations, where the evolution of fluxes at a single node may involve time-delayed terms from all other nodes. Thus we propose an alternative hybrid approach, introducing additional logic variables. Finally we compute the effects of variations on permeability parameters over the hybrid dynamics and test the obtained results via simulations.

  19. A complex permittivity and permeability measurement system for elevated temperatures

    NASA Technical Reports Server (NTRS)

    Friederich, Paul

    1990-01-01

    The three goals of this research include: (1) to fully develop a method to measure the permittivity and permeability of special materials as a function of frequency in the range of 2.6 to 18 GHz, and of temperatures in the range of 25 to 1100 C; (2) to assist LeRC in setting up an in-house system for the measurement of high-temperature permittivity and permeability; and (3) to measure the complex permittivity and permeability of special materials as a function of frequency and temperature to demonstrate the capability of the method. The method chosen for characterizing the materials relies on perturbation of a resonant cavity with a small volume of sample material. Different field configurations in the cavity can be used to separate electric and magnetic effects. The cavity consists of a section of rectangular waveguide terminated at each end of a vertical slot iris. The center of one wall is a small hole through which the sample is introduced.

  20. A complex permittivity and permeability measurement system for elevated temperatures

    NASA Technical Reports Server (NTRS)

    Friederich, Paul

    1990-01-01

    The three goals of this research include: (1) to fully develop a method to measure the permittivity and permeability of special materials as a function of frequency in the range of 2.6 to 18 GHz, and of temperature in the range of 25 to 1100 C; (2) to assist LeRC in setting up an in-house system for the measurement of high-temperature permittivity and permeability; and (3) to measure the complex permittivity and permeability of special materials as a function of frequency and temperature to demonstrate the capability of the method. The method chosen for characterizing the materials relies on perturbation of a resonant cavity with a small volume of sample material. Different field configurations in the cavity can be used to separate electric and magnetic effects. The cavity consists of a section of rectangular waveguide terminated at each end of a vertical slot iris. In the center of one wall is a small hole through which the sample is introduced.

  1. Permeability Modification Using a Reactive Alkaline-Soluble Biopolymer

    SciTech Connect

    Sandra L. Fox; Xina Xie; Greg Bala

    2004-11-01

    Polymer injection has been used in reservoirs to alleviate contrasting permeability zones to enhance oil recovery (EOR). Polymer technology relies mainly on the use of polyacrylamides cross-linked by a hazardous metal or organic. Contemporary polymer plugging has investigated the stimulation of in-situ microorganisms to produce polymers (Jenneman et. al., 2000) and the use of biocatalysts to trigger gelling (Bailey et. al., 2000). The use of biological polymers are advantageous in that they can block high permeability areas, are environmentally friendly, and have potential to form reversible gels without the use of hazardous cross-linkers. Recent efforts have produced a reactive alkaline-soluble biopolymer from Agrobacterium species ATCC # 31749 that gels upon decreasing the pH of the polymeric solution. Microbial polymers are of interest due to their potential cost savings, compared to conventional use of synthetic chemical polymers. Numerous microorganisms are known to produce extracellular polysaccharides. One microbiological polymer of interest is curdlan, â - (1, 3) glucan, which has demonstrated gelling properties by a reduction in pH. The focus of this study was to determine the impact an alkaline-soluble biopolymer can have on sandstone permeability.

  2. Permeability tensor and representative elementary volume of fractured rock masses

    NASA Astrophysics Data System (ADS)

    Rong, Guan; Peng, Jun; Wang, Xiaojiang; Liu, Guang; Hou, Di

    2013-11-01

    Based on a simulation of three-dimensional fracture networks and a superposition principle of liquid dissipation energy for fractured rock masses, a model of the fracture permeability tensor is proposed. An elastic constitutive model of rock fractures, considering fracture closure and dilation during shearing, is also proposed, based on the dilation angle of the fracture. Algorithms of flow-path searching and calculation of the effective flow coefficients for fracture networks are presented, together with a discussion on the influence of geometric parameters of the fractures (trace length, spacing, aperture, orientation and the number of fracture sets) on magnitude, anisotropy of hydraulic permeability and the size of a representative elementary volume (REV). The anisotropy of hydraulic permeability of fractured rock masses is mainly affected by orientation and the number of fracture sets, and the REV size is mainly influenced by trace length, spacing and the number of fracture sets. The results of studies on REV size and the influence of in-situ stress on hydraulic conductivity of the rock mass on the slope of Jinping-I hydropower station, China, are presented using the developed models and methods. The simulation results agreed well with the results obtained from field water-pressure measurements, with an error of less than 10 %.

  3. Permeability Coefficients of Lipophilic Compounds Estimated by Computer Simulations.

    PubMed

    Ghaemi, Zhaleh; Alberga, Domenico; Carloni, Paolo; Laio, Alessandro; Lattanzi, Gianluca

    2016-08-01

    The ability of a drug to cross the intestine-blood barrier is a key quantity for drug design and employment and is normally quantified by the permeability coefficient P, often evaluated in the so-called Caco-2 assay. This assay is based on measuring the initial growth rate of the concentration of the drug beyond the cellular barrier but not its steady-state flux through the membrane. This might lead to confusion since, in the case of lipophilic drugs, the initial slope is strongly affected by the retention of the drug in the membrane. This effect is well known but seldom considered in the assay. Here, we exploit all-atoms molecular dynamics and bias exchange metadynamics to calculate the concentration of two lipophilic drugs across a model membrane as a function of time. This allows estimating both the steady-state flux and the initial slope of the concentration growth and comparing Caco-2 and steady-state estimates of P. We show that our computational procedure is able to reproduce the experimental values, although these may differ from the permeability coefficients by orders of magnitude. Our findings are generalized by a simplified one-dimensional model of the permeation process that may act as a roadmap to assess which measure of membrane permeability would be more appropriate and, consequently, whether retention corrections should be included in estimates based on Caco-2 assays. PMID:27392273

  4. Optimizing water permeability through the hourglass shape of aquaporins.

    PubMed

    Gravelle, Simon; Joly, Laurent; Detcheverry, François; Ybert, Christophe; Cottin-Bizonne, Cécile; Bocquet, Lydéric

    2013-10-01

    The ubiquitous aquaporin channels are able to conduct water across cell membranes, combining the seemingly antagonist functions of a very high selectivity with a remarkable permeability. Whereas molecular details are obvious keys to perform these tasks, the overall efficiency of transport in such nanopores is also strongly limited by viscous dissipation arising at the connection between the nanoconstriction and the nearby bulk reservoirs. In this contribution, we focus on these so-called entrance effects and specifically examine whether the characteristic hourglass shape of aquaporins may arise from a geometrical optimum for such hydrodynamic dissipation. Using a combination of finite-element calculations and analytical modeling, we show that conical entrances with suitable opening angle can indeed provide a large increase of the overall channel permeability. Moreover, the optimal opening angles that maximize the permeability are found to compare well with the angles measured in a large variety of aquaporins. This suggests that the hourglass shape of aquaporins could be the result of a natural selection process toward optimal hydrodynamic transport. Finally, in a biomimetic perspective, these results provide guidelines to design artificial nanopores with optimal performances. PMID:24067650

  5. Review of potential subsurface permeable barrier emplacement and monitoring technologies

    SciTech Connect

    Riggsbee, W.H.; Treat, R.L.; Stansfield, H.J.; Schwarz, R.M.; Cantrell, K.J.; Phillips, S.J.

    1994-02-01

    This report focuses on subsurface permeable barrier technologies potentially applicable to existing waste disposal sites. This report describes candidate subsurface permeable barriers, methods for emplacing these barriers, and methods used to monitor the barrier performance. Two types of subsurface barrier systems are described: those that apply to contamination.in the unsaturated zone, and those that apply to groundwater and to mobile contamination near the groundwater table. These barriers may be emplaced either horizontally or vertically depending on waste and site characteristics. Materials for creating permeable subsurface barriers are emplaced using one of three basic methods: injection, in situ mechanical mixing, or excavation-insertion. Injection is the emplacement of dissolved reagents or colloidal suspensions into the soil at elevated pressures. In situ mechanical mixing is the physical blending of the soil and the barrier material underground. Excavation-insertion is the removal of a soil volume and adding barrier materials to the space created. Major vertical barrier emplacement technologies include trenching-backfilling; slurry trenching; and vertical drilling and injection, including boring (earth augering), cable tool drilling, rotary drilling, sonic drilling, jetting methods, injection-mixing in drilled holes, and deep soil mixing. Major horizontal barrier emplacement technologies include horizontal drilling, microtunneling, compaction boring, horizontal emplacement, longwall mining, hydraulic fracturing, and jetting methods.

  6. Wake control with permeable multilayer structures: The spherical symmetry case.

    PubMed

    Bowen, Patrick T; Smith, David R; Urzhumov, Yaroslav A

    2015-12-01

    We explore the possibility of controlling the wake and drag of a spherical object independently of each other, using radial distributions of permeability in the Brinkman-Stokes formalism. By discretizing a graded-permeability shell into discrete, macroscopically homogeneous layers, we are able to sample the entire functional space of spherically-symmetric permeabilities and observe quick convergence to a certain manifold in the wake-drag coordinates. Monte Carlo samplings with 10^{4}-10^{5} points have become possible thanks to our new algorithm, which is based on exact analytical solutions for the Stokes flow through an arbitrary multilayer porous sphere. The algorithm is not restricted to the Brinkman-Stokes equation and can be modified to account for other types of scattering problems for spherically-symmetric systems with arbitrary radial complexity. Our main practical finding for Stokes flow is that it is possible to reduce a certain measure of wake of a spherical object without any energy penalty and without active (power-consuming) force generation. PMID:26764826

  7. Optimizing water permeability through the hourglass shape of aquaporins

    PubMed Central

    Gravelle, Simon; Joly, Laurent; Detcheverry, François; Ybert, Christophe; Cottin-Bizonne, Cécile; Bocquet, Lydéric

    2013-01-01

    The ubiquitous aquaporin channels are able to conduct water across cell membranes, combining the seemingly antagonist functions of a very high selectivity with a remarkable permeability. Whereas molecular details are obvious keys to perform these tasks, the overall efficiency of transport in such nanopores is also strongly limited by viscous dissipation arising at the connection between the nanoconstriction and the nearby bulk reservoirs. In this contribution, we focus on these so-called entrance effects and specifically examine whether the characteristic hourglass shape of aquaporins may arise from a geometrical optimum for such hydrodynamic dissipation. Using a combination of finite-element calculations and analytical modeling, we show that conical entrances with suitable opening angle can indeed provide a large increase of the overall channel permeability. Moreover, the optimal opening angles that maximize the permeability are found to compare well with the angles measured in a large variety of aquaporins. This suggests that the hourglass shape of aquaporins could be the result of a natural selection process toward optimal hydrodynamic transport. Finally, in a biomimetic perspective, these results provide guidelines to design artificial nanopores with optimal performances. PMID:24067650

  8. Temperature sensitivity of Ottawa sand and Massillon sandstone intrinsic permeabilities

    SciTech Connect

    Stottlemyre, J.A.; Cooley, C.H.; Banik, G.J.

    1981-03-01

    Aquifer Thermal Energy Storage (ATES) involves the seasonal storage of surplus, low enthalpy energy. A typical scheme might involve withdrawing a few hundred gallons per minute of water from an aquifer, passing the groundwater through a heat exchanger where its temperature is increased via indirect contact with surplus heat from an electric generating or industrial processing plant, and then reinjecting and storing the heated groundwater in the original aquifer. The heat might be ultimately withdrawn and used for space heating or commercial applications. It has been estimated that it may be technically feasible to supply about 7.5% of the nation's total energy demand through aquifer thermal energy storage. However, certain unknowns remain including cost effectiveness, institutional and legal problems, and the physicochemical stability of the storage aquifer. This paper is a summary of a laboratory study focused on the component of the reservoir stability question, the temperature sensitivity of sand and sandstone intrinsic permeabilities. Ottawa sand and Massillon sandstone samples were exposed to a hydrostatic confining pressure of 150 bars, a pore fluid pressure of 60 bars, and temperatures between 25 and 150/sup 0/C. Permeability to deionized, deaerated, prefilitered water and calcium chloride solution, bulk volumetric strain, fluid chemistry, and particle carryover were monitored as a function of temperature and time. Potential permeability damage mechanisms were investigated including porosity reduction via bulk compaction, porosity reduction due to thermal expansion of constituent minerals, and thermally-induced internal and/or external particle plugging.

  9. Image-based relative permeability upscaling from the pore scale

    NASA Astrophysics Data System (ADS)

    Norouzi Apourvari, Saeid; Arns, Christoph H.

    2016-09-01

    High resolution images acquired from X-ray μ-CT are able to map the internal structure of porous media on which multiphase flow properties can be computed. While the resolution of a few micrometers may be sufficient for capturing the pore space of many sandstones, most carbonates exhibit a large amount of microporosity; pores which are below the image resolution and are not resolved at specific resolution. Neglecting the effect of micropores on fluid flow and transport properties of these rocks can cause erroneous results in particular at partial saturations. Current image-based pore scale models typically only consider macropores for simulating fluid flow. In this paper, we quantify the effect of microporosity on the effective permeability of the wetting phase for heterogeneous model structures with varying amount of micro-to-macro porosity. A multi-scale numerical approach is proposed to couple an average effect of micropores with an explicit representation of macropores. The Brinkman equation is solved using a lattice Boltzmann formulation to facilitate the coupling of Darcy and Stokes equations in micropores and macropores, respectively. The results show good agreement between the fine scale solution and the results of the upscaled models in which microporous regions are homogenised. The paper analyses in particular the choice of the momentum sink parameter at low wetting phase saturations. It is shown that this parameter can be found using either a flux-based calculation of permeability of microporous regions or chosen purely on the basis of the effective permeability of these regions.

  10. Permeability inhomogeneity accounting in terms of efficient development strategy

    NASA Astrophysics Data System (ADS)

    Korovin, M. O.; Merkulov, V. P.; Gojkovic, S. Z.

    2015-02-01

    The main questions concerning flow and permeability anisotropy are: presence of anisotropy (is a reservoir anisotropic or not), orientation and degree of anisotropy. Answers were obtained through the analysis of grain fabric, spatial permeability spread and tracer injection data. The magnitude of permeability was determined to be within a range from 0.5 to 1 and with the azimuth of 48 from the North. Thereafter, the incorporation of new information about field K into the simulation model matched and the comparison of isotropic (the existing model) and anisotropic (the model upgraded with novel information) were performed. This process showed that the simple introduction of obtained anisotropy properties improved the history match, which was interpreted as the proof of anisotropy being present on both the macroscopic and microscopic scale. At the end, general recommendations for the optimal production practice in the anisotropic reservoir were proposed and the potential strategy for further development was suggested. This optimal strategy was created by changing several producing wells into injectors and it resulted in an overall oil production increase and individual well production increase amounting to as much as 20%.

  11. Iron abundance and magnetic permeability of the moon

    NASA Technical Reports Server (NTRS)

    Parkin, C. W.; Daily, W. D.; Dyal, P.

    1974-01-01

    A larger set of simultaneous data from the Apollo 12 lunar surface magnetometer and the Explorer 35 Ames magnetometer are used to construct a whole-moon hysteresis curve, from which a new value of global lunar permeability is determined to be mu = 1.012 + or - 0.006. The corresponding global induced dipole moment is 2.1 x 10 to the 18th power gauss-cu cm for typical inducing fields of .0001 gauss in the lunar environment. From the permeability measurement, lunar free iron abundance is determined to be 2.5 + or - 2.0 wt. %. Total iron abundance (sum of iron in the ferromagnetic and paramagnetic states) is calculated for two assumed compositional models of the lunar interior: a free iron/orthopyroxene lunar composition and a free iron/olivine composition. The overall lunar total iron abundance is determined to be 9.0 + or - 4.7 wt. %. Other lunar models with a small iron core and with a shallow iron-rich layer are discussed in light of the measured global permeability.

  12. Wake control with permeable multilayer structures: The spherical symmetry case.

    PubMed

    Bowen, Patrick T; Smith, David R; Urzhumov, Yaroslav A

    2015-12-01

    We explore the possibility of controlling the wake and drag of a spherical object independently of each other, using radial distributions of permeability in the Brinkman-Stokes formalism. By discretizing a graded-permeability shell into discrete, macroscopically homogeneous layers, we are able to sample the entire functional space of spherically-symmetric permeabilities and observe quick convergence to a certain manifold in the wake-drag coordinates. Monte Carlo samplings with 10^{4}-10^{5} points have become possible thanks to our new algorithm, which is based on exact analytical solutions for the Stokes flow through an arbitrary multilayer porous sphere. The algorithm is not restricted to the Brinkman-Stokes equation and can be modified to account for other types of scattering problems for spherically-symmetric systems with arbitrary radial complexity. Our main practical finding for Stokes flow is that it is possible to reduce a certain measure of wake of a spherical object without any energy penalty and without active (power-consuming) force generation.

  13. Volume-induced increase of anion permeability in human lymphocytes.

    PubMed

    Grinstein, S; Clarke, C A; Dupre, A; Rothstein, A

    1982-12-01

    Peripheral blood mononuclear cells (PBM) readjust their volumes after swelling in hypotonic media. This regulatory volume decrease (RVD) is associated with a loss of cellular K+ and is thought to be promoted by an increased permeability to this ion. In contrast, no change in volume was observed when K+ permeability of PBM in isotonic media was increased to comparable or higher levels using valinomycin. Moreover, valinomycin-induced 86Rb+ loss in K+-free medium was considerably slower than in K+-rich medium. These results suggest that anion conductance limits net salt loss in isotonic media. Direct measurements of relative conductance confirmed that in volume-static cells, anion conductance is lower than that of K+. In volume-regulating cells depolarization occurred presumably as a result of increased anion conductance. Accordingly, the efflux of 36Cl from PBM was markedly increased by hypotonic stress. Since both membrane potential and intracellular 36Cl concentration are reduced in hypotonically swollen cells, the increased efflux is probably due to a change in Cl- permeability. Anions and cations seem to move independently through the volume-induced pathways: the initial rate of 86Rb uptake in swollen cells was not affected by replacement of external Cl- by SO=4; conversely, 36Cl fluxes were unaffected by substitution of K+ by Na+. The data indicate that anion conductance is rate-determining in salt and water loss from PBM. An increase in anion conductance is suggested to be the critical step of RVD of human PBM.

  14. Discovery sequence and the nature of low permeability gas accumulations

    USGS Publications Warehouse

    Attanasi, E.D.

    2005-01-01

    There is an ongoing discussion regarding the geologic nature of accumulations that host gas in low-permeability sandstone environments. This note examines the discovery sequence of the accumulations in low permeability sandstone plays that were classified as continuous-type by the U.S. Geological Survey for the 1995 National Oil and Gas Assessment. It compares the statistical character of historical discovery sequences of accumulations associated with continuous-type sandstone gas plays to those of conventional plays. The seven sandstone plays with sufficient data exhibit declining size with sequence order, on average, and in three of the seven the trend is statistically significant. Simulation experiments show that both a skewed endowment size distribution and a discovery process that mimics sampling proportional to size are necessary to generate a discovery sequence that consistently produces a statistically significant negative size order relationship. The empirical findings suggest that discovery sequence could be used to constrain assessed gas in untested areas. The plays examined represent 134 of the 265 trillion cubic feet of recoverable gas assessed in undeveloped areas of continuous-type gas plays in low permeability sandstone environments reported in the 1995 National Assessment. ?? 2005 International Association for Mathematical Geology.

  15. A microscopic multiphase diffusion model of viable epidermis permeability.

    PubMed

    Nitsche, Johannes M; Kasting, Gerald B

    2013-05-21

    A microscopic model of passive transverse mass transport of small solutes in the viable epidermal layer of human skin is formulated on the basis of a hexagonal array of cells (i.e., keratinocytes) bounded by 4-nm-thick, anisotropic lipid bilayers and separated by 1-μm layers of extracellular fluid. Gap junctions and tight junctions with adjustable permeabilities are included to modulate the transport of solutes with low membrane permeabilities. Two keratinocyte aspect ratios are considered to represent basal and spinous cells (longer) and granular cells (more flattened). The diffusion problem is solved in a unit cell using a coordinate system conforming to the hexagonal cross section, and an efficient two-dimensional treatment is applied to describe transport in both the cell membranes and intercellular spaces, given their thinness. Results are presented in terms of an effective diffusion coefficient, D¯(epi), and partition coefficient, K¯(epi/w), for a homogenized representation of the microtransport problem. Representative calculations are carried out for three small solutes-water, L-glucose, and hydrocortisone-covering a wide range of membrane permeability. The effective transport parameters and their microscopic interpretation can be employed within the context of existing three-layer models of skin transport to provide more realistic estimates of the epidermal concentrations of topically applied solutes.

  16. Contribution of the Kallikrein/Kinin System to the Mediation of ConA-Induced Inflammatory Ascites.

    PubMed

    Baintner, Károly

    2016-03-01

    Intraperitoneal administration of concanavalin A (ConA, 25 mg/kg b.w.), a cell-binding plant lectin was used for inducing inflammatory ascites, and potential inhibitors were tested in 1 h and 2.5 h experiments, i.e. still before the major influx of leucocytes. At the end of the experiment the peritoneal fluid was collected and measured. The ConA-induced ascites was significantly (p<0.01) and dose-dependently inhibited by icatibant (HOE-140), a synthetic polypeptide antagonist of bradykinin receptors. Aprotinin, a kallikrein inhibitor protein also had significant (p<0.01), but less marked inhibitory effect. L-NAME, an inhibitor of NO synthesis, and atropine methylnitrate, an anticholinergic compound, were ineffective. It is concluded, that the kallikrein/kinin system contributes to the mediation of the ConA-induced ascites by increasing subperitoneal vascular permeability, independent of the eventual vasodilation produced by NO. It is known, that membrane glycoproteins are aggregated by the tetravalent ConA and the resulting distortion of membrane structure may explain the activation of the labile prekallikrein. Complete inhibition of the ConA-induced ascites could not be achieved by aprotinin or icatibant, which indicates the involvement of additional mediators. PMID:27020875

  17. Beach protection by a system of permeable groins

    NASA Astrophysics Data System (ADS)

    Boczar-Karakiewicz, B.; Romanczyk, W.; Roy, N.

    2002-12-01

    A new type of permeable groin (called System of Groins Maltec-Savard - SGMS) has been installed at three eroded sites located in the coastal area on the north shore of the St. Lawrence, Quebec, Canada. In this area, the narrow sandy beaches with sandy or sand-silty cliff of variable height (10-15~m) are exposed to obliquely incident waves arriving from both west (summer) and east (autumn), and to tidal currents (maximum tidal rate is 4.3~m). The periods of summer waves equal 3-5~s, with wave heights of about 0.4-0.7~m. In the autumn, major storm waves reach periods of up to 7-10~s, with wave heights of 1.0-1.2~m. The new groins are sediment traps formed by a central double and permeable groin with several smaller lateral, groins installed on one or both sides of the central groin (Boczar-Karakiewicz et al., 2001). The permeable central and lateral groins are structured by inserting double ranges of wooden piles (diameter of about 10 cm). The space between the ranges of piles (some 0.8~m wide) is filled with tree branches (e.g., the top parts of pine trees, a waste product of the local forest industry). A permeable grid covering the top of the groins forms a cage that holds the branches in place. The lateral groins, are identical but much shorter than the central groin. The whole system dissipates the incident energy of wave- and tidally-generated currents and causes accretion of sand transported by these currents. The GSMS also allows the by-pass of some sediment to adjacent zones without groins. Observations and results of measurements from three experiments field show that: (1) a sandy beach in front of a coastal cliff secures its stability and attenuates the erosion caused by waves and tidal currents; (2) permeability and flexibility of the SGMS causes the accretion of sediment in the protected area without erosion in the neighboring zones; (3) the SGMS does not generate wave reflection and any secondary current; (4) the materials of the groins are easily

  18. BBB-Permeable, Neuroprotective, and Neurotrophic Polysaccharide, Midi-GAGR

    PubMed Central

    Makani, Vishruti; Jang, Yong-gil; Christopher, Kevin; Judy, Wesley; Eckstein, Jacob; Hensley, Kenneth; Chiaia, Nicolas; Kim, Dong-Shik; Park, Joshua

    2016-01-01

    An enormous amount of efforts have been poured to find an effective therapeutic agent for the treatment of neurodegenerative diseases including Alzheimer’s disease (AD). Among those, neurotrophic peptides that regenerate neuronal structures and increase neuron survival show a promise in slowing neurodegeneration. However, the short plasma half-life and poor blood-brain-barrier (BBB)-permeability of neurotrophic peptides limit their in vivo efficacy. Thus, an alternative neurotrophic agent that has longer plasma half-life and better BBB-permeability has been sought for. Based on the recent findings of neuroprotective polysaccharides, we searched for a BBB-permeable neuroprotective polysaccharide among natural polysaccharides that are approved for human use. Then, we discovered midi-GAGR, a BBB-permeable, long plasma half-life, strong neuroprotective and neurotrophic polysaccharide. Midi-GAGR is a 4.7kD cleavage product of low acyl gellan gum that is approved by FDA for human use. Midi-GAGR protected rodent cortical neurons not only from the pathological concentrations of co-/post-treated free reactive radicals and Aβ42 peptide but also from activated microglial cells. Moreover, midi-GAGR showed a good neurotrophic effect; it enhanced neurite outgrowth and increased phosphorylated cAMP-responsive element binding protein (pCREB) in the nuclei of primary cortical neurons. Furthermore, intra-nasally administered midi-GAGR penetrated the BBB and exerted its neurotrophic effect inside the brain for 24 h after one-time administration. Midi-GAGR appears to activate fibroblast growth factor receptor 1 (FGFR1) and its downstream neurotrophic signaling pathway for neuroprotection and CREB activation. Additionally, 14-day intranasal administration of midi-GAGR not only increased neuronal activity markers but also decreased hyperphosphorylated tau, a precursor of neurofibrillary tangle, in the brains of the AD mouse model, 3xTg-AD. Taken together, midi-GAGR with good BBB-permeability

  19. Effects of pore-scale precipitation on permeability and flow

    NASA Astrophysics Data System (ADS)

    Noiriel, Catherine; Steefel, Carl I.; Yang, Li; Bernard, Dominique

    2016-09-01

    The effects of calcite precipitation on porous media permeability and flow were evaluated with a combined experimental and modeling approach. X-ray microtomography images of two columns packed with glass beads and calcite (spar crystals) or aragonite (Bahamas ooids) injected with a supersaturated solution (log Ω = 1.42) were processed in order to calculate rates of calcite precipitation with a spatial resolution of 4.46 μm. Identification and localization of the newly precipitated crystals on the 3D images was performed and results used to calculate the crystal growth rates and velocities. The effects of carbonate precipitation were also evaluated in terms of the integrated precipitation rate over the length of the column, crystal shape, surface area and pore roughness changes. While growth was epitaxial on calcite spar, calcite rhombohedra formed on glass beads and clusters of polyhedrons formed on aragonite ooids. Near the column inlet, calcite precipitation occurred preferentially on carbonate grains compared to glass beads, with almost 100% of calcite spar surface area covered by new crystals versus 92% in the case of aragonite and 11% in the case of glass beads. Although the experimental chemistry and flow boundary conditions in the two columns were similar, their porosity-permeability evolution was different because the nucleation and subsequent crystal growth on the two substrates (i.e., calcite spar and aragonite ooids) was very different. The impact of mineral precipitation on pore-scale flow and permeability was evaluated using a pore-scale Stokes solver that accounted for the changes in pore geometry. For similar magnitude reductions in porosity, the decrease in permeability was highest within the sample that experienced the greatest increase in pore roughness. Various porous media models were generated to show the impact of different crystal growth patterns and pore roughness changes on flow and permeability-porosity relationship. Under constant flow

  20. An assay for permeability of the zebrafish embryonic neuroepithelium.

    PubMed

    Chang, Jessica T; Sive, Hazel

    2012-10-24

    The brain ventricular system is conserved among vertebrates and is composed of a series of interconnected cavities called brain ventricles, which form during the earliest stages of brain development and are maintained throughout the animal's life. The brain ventricular system is found in vertebrates, and the ventricles develop after neural tube formation, when the central lumen fills with cerebrospinal fluid (CSF) (1,2). CSF is a protein rich fluid that is essential for normal brain development and function(3-6). In zebrafish, brain ventricle inflation begins at approximately 18 hr post fertilization (hpf), after the neural tube is closed. Multiple processes are associated with brain ventricle formation, including formation of a neuroepithelium, tight junction formation that regulates permeability and CSF production. We showed that the Na,K-ATPase is required for brain ventricle inflation, impacting all these processes (7,8), while claudin 5a is necessary for tight junction formation (9). Additionally, we showed that "relaxation" of the embryonic neuroepithelium, via inhibition of myosin, is associated with brain ventricle inflation. To investigate the regulation of permeability during zebrafish brain ventricle inflation, we developed a ventricular dye retention assay. This method uses brain ventricle injection in a living zebrafish embryo, a technique previously developed in our lab(10), to fluorescently label the cerebrospinal fluid. Embryos are then imaged over time as the fluorescent dye moves through the brain ventricles and neuroepithelium. The distance the dye front moves away from the basal (non-luminal) side of the neuroepithelium over time is quantified and is a measure of neuroepithelial permeability (Figure 1). We observe that dyes 70 kDa and smaller will move through the neuroepithelium and can be detected outside the embryonic zebrafish brain at 24 hpf (Figure 2). This dye retention assay can be used to analyze neuroepithelial permeability in a

  1. In vivo analysis of intestinal permeability following hemorrhagic shock

    PubMed Central

    Alsaigh, Tom; Chang, Marisol; Richter, Michael; Mazor, Rafi; Kistler, Erik B

    2015-01-01

    AIM: To determine the time course of intestinal permeability changes to proteolytically-derived bowel peptides in experimental hemorrhagic shock. METHODS: We injected fluorescently-conjugated casein protein into the small bowel of anesthetized Wistar rats prior to induction of experimental hemorrhagic shock. These molecules, which fluoresce when proteolytically cleaved, were used as markers for the ability of proteolytically cleaved intestinal products to access the central circulation. Blood was serially sampled to quantify the relative change in concentration of proteolytically-cleaved particles in the systemic circulation. To provide spatial resolution of their location, particles in the mesenteric microvasculature were imaged using in vivo intravital fluorescent microscopy. The experiments were then repeated using an alternate measurement technique, fluorescein isothiocyanate (FITC)-labeled dextrans 20, to semi-quantitatively verify the ability of bowel-derived low-molecular weight molecules (< 20 kD) to access the central circulation. RESULTS: Results demonstrate a significant increase in systemic permeability to gut-derived peptides within 20 min after induction of hemorrhage (1.11 ± 0.19 vs 0.86 ± 0.07, P < 0.05) compared to control animals. Reperfusion resulted in a second, sustained increase in systemic permeability to gut-derived peptides in hemorrhaged animals compared to controls (1.2 ± 0.18 vs 0.97 ± 0.1, P < 0.05). Intravital microscopy of the mesentery also showed marked accumulation of fluorescent particles in the microcirculation of hemorrhaged animals compared to controls. These results were replicated using FITC dextrans 20 [10.85 ± 6.52 vs 3.38 ± 1.11 fluorescent intensity units (× 105, P < 0.05, hemorrhagic shock vs controls)], confirming that small bowel ischemia in response to experimental hemorrhagic shock results in marked and early increases in gut membrane permeability. CONCLUSION: Increased small bowel permeability in hemorrhagic

  2. Flow Characteristics in Permeable Reactive Barrier Affected by Biological Clogging

    NASA Astrophysics Data System (ADS)

    Seki, K.; Hanada, J.; Miyazaki, T.

    2004-12-01

    Permeable reactive barriers (PRB) are becoming popular for the in situ remediation of contaminated groundwater. The efficiency of the PRB is affected by permeability of the reactive zone, because when permeability decreases contaminants can bypass the reactive zone without degraded. One of the factors affecting permeability of the permeable reactive zone is biological clogging of soil pore, i.e., biomass buildup and resultant decrease in hydraulic conductivity. So far biological clogging in laboratory was mostly observed in one-dimensional flow field, but the actual flow field in PRB is better simulated in two-dimensional flow field. The objective of this study is to observe the flow characteristics in PRB by using simulated flow cells in laboratory, by comparing one-dimensional and two-dimensional flow field. One-dimensional flow field was simulated by 20 cm length and 1 cm width flow cell, and two-dimensional flow field was simulated by 20 cm length and 10 cm width flow cell. Each flow cell was operated under water-saturated conditions, in horizontal position, and at a constant temperature of 20 degree centigrade. Glass beads of 0.1 mm mean diameter was packed uniformly in the flow cells and inoculum was injected into the nutrient injection ports at the middle of the flow cells. After 24 h incubation time continuous flow was started. Background flow of de-ionized water was supplied to the inlet ports, and the mineral medium was supplied from the nutrient injection ports. The flux was measured every day and local hydraulic head distribution was measured by water manometer, and hydraulic conductivity was calculated. The flow cell experiments were continued for 9 days. In one-dimensional flow cell, hydraulic conductivity of the nutrient supplied part decreased to about half of the initial value in 9 days flow period, where the hydraulic conductivity of the part where nutrient was not supplied remained constant. Bacterial and fungal number in the moderately clogged

  3. Effects of ozone on airway epithelial permeability and ion transport.

    PubMed

    Bromberg, P A; Ranga, V; Stutts, M J

    1991-12-01

    Ozone is a highly reactive form of oxygen produced in the atmosphere by photochemical reactions involving substrates emitted from automobile engines. Outdoor air concentrations as high as 0.4 parts per million (ppm) occur. The respiratory tract extracts about 90% of inhaled ozone. From the chemical reactivity of ozone, it is expected to attack organic molecules located on or near the respiratory surfaces. The airways are covered with a cohesive layer of epithelial cells that forms the boundary between the external environment and the respiratory tissues. One important role of this epithelial layer is its barrier function. Airborne particles that deposit (and dissolve) in the airway surface liquid are not readily absorbed, and soluble tissue components are excluded from the surface liquid. The epithelium also controls the volume and composition of the surface liquid. One important process in this regard is the absorption and secretion of ions and water. We have studied the effects of inhalation of ozone on the barrier function (permeability to dissolved molecules) and the ion transport activity of epithelium using both in vivo and in vitro techniques. All our experiments were performed with male Hartley strain guinea pigs. Conscious, unrestrained animals were exposed to a concentration of ozone of 1 ppm for three hours in controlled environmental chambers in the Health Effects Research Laboratory, U.S. Environmental Protection Agency (EPA), Research Triangle Park, NC. Such exposures caused a marked increase in the rate of appearance in blood of various water-soluble compounds instilled onto the surface of the trachea, indicating increased permeability of the airway epithelium. This interpretation was supported by electron microscopy, which showed that the tracer molecule horseradish peroxidase was present in the intercellular spaces of tracheal epithelium from ozone-exposed, but not air-exposed (control), animals. However, when the tracheas were excised after ozone

  4. Effect of Permeability of Tipping Paper on Cigarette Burning Temperature and the Property of Mainstream Smoke

    NASA Astrophysics Data System (ADS)

    Yao, Zhen-Yu; Shen, Yan; Huang, Hai-Qun; Xu, Ji-Cang

    2016-05-01

    Cigarette smoke analysis of tipping paper with different permeability was carried out. The infrared thermal imager was used to measure burning temperature of cigarette with different permeability tipping paper. The results indicated that with the increase of tipping paper permeability, Tar, CO and nicotine in cigarette mainstream were significantly linear decreased, puff count was increased. Tipping paper permeability had a great influence on cigarette burning temperature. With the increase of tipping paper permeability, the third puff burning temperature and the average peak temperature values were dropped obviously, but the changes of smoldering temperature were not obvious. In addition, smoldering average temperature was significantly lower than the third puff burning temperature and peak temperature.

  5. Permeability testing of fractures in climax stock granite at the Nevada Test Site

    SciTech Connect

    Murray, W.A.

    1980-12-31

    Permeability tests conducted in the Climax stock granitic rock mass indicate that the bulk rock permeability can be highly variable. If moderately to highly fractured zones are encountered, the permeability values may lie in the range of 10{sup -4} to 10{sup -1} darcies. If, on the other hand, only intact rock or healed fractures are encountered, the permeability is found to be less than 10{sup -9} darcies. In order to assess the thermomechanical effect on fracture permeability, discrete fractures will be packed off and tested periodically throughout the thermal cycle caused by the emplacement of spent nuclear fuel in the Climax stock.

  6. Human Disc Nucleus Properties and Vertebral Endplate Permeability

    PubMed Central

    Rodriguez, Azucena G.; Slichter, Chloe K.; Acosta, Frank L.; Rodriguez-Soto, Ana E.; Burghardt, Andrew J.; Majumdar, Sharmila; Lotz, Jeffrey C.

    2010-01-01

    Study of human cadaveric discs quantifying endplate permeability and porosity and correlating these with measures of disc quality: cell density, proteoglycan content, and overall degeneration. Permeability and porosity increased with age and were not correlated with cell density or overall degeneration, suggesting that endplate calcification may not accelerate disc degeneration. Study Design Experimental quantification of relationships between vertebral endplate morphology, permeability, disc cell density, glycosaminoglycan content and degeneration in samples harvested from human cadaveric spines. Objective To test the hypothesis that variation in endplate permeability and porosity contribute to changes in intervertebral disc cell density and overall degeneration. Summary of Background Data Cells within the intervertebral disc are dependent on diffusive exchange with capillaries in the adjacent vertebral bone. Previous findings suggest that blocked routes of transport negatively affect disc quality, yet there are no quantitative relationships between human vertebral endplate permeability, porosity, cell density and disc degeneration. Such relationships would be valuable for clarifying degeneration risk factors, and patient features that may impede efforts at disc tissue engineering. Methods Fifty-one motion segments were harvested from 13 frozen cadaveric human lumbar spines (32 to 85 years) and classified for degeneration using the MRI-based Pfirrmann scale. A cylindrical core was harvested from the center of each motion segment that included vertebral bony and cartilage endplates along with adjacent nucleus tissue. The endplate mobility, a type of permeability, was measured directly using a custom-made permeameter before and after the cartilage endplate was removed. Cell density within the nucleus tissue was estimated using the picogreen method while the nuclear GAG content was quantified using the DMMB technique. Specimens were imaged at 8 μm resolution using

  7. Permeability, drying, and sintering of pressure filtered ceramic nanopowders

    NASA Astrophysics Data System (ADS)

    Sweeney, Sean M.

    2002-01-01

    Three aspects of nanocrystalline ceramic body formation are examined in this work: permeability, drying stress, and sintering behavior. The permeabilities of nanocrystalline 3 mol% yttria-stabilized zirconia (3Y-TZP), silica, and boehmite powder compacts are measured during their formation by constant rate pressure filtration. The classic Carman-Kozeny equation with no account for the effect of adsorbed water often overestimates by a factor of 2 or more the measured permeabilities, with increasing deviation with decreasing permeability. A permeability equation from the literature and one derived here, both taking into account the effect of adsorbed water, show significant improvement over the classic Carman-Kozeny equation for predicting measured permeabilities. The equation derived here allows straightforward predictions to be made of how permeability will change as the critical point of drying (when shrinkage stops) is approached. An approximate expression for the maximum tensile stress occurring in an elastic finite cylinder during drying from all sides is derived. Numerical calculations of the exact state of stress during drying show that for cylinder length-to-diameter ratios up to 2/3, the present expression is more accurate than equations from the literature for an infinite plate and an infinite cylinder. For cylinders with length-to-diameter ratios greater than 2/3, numerical calculations show an equation from the literature for the drying stress in an infinite cylinder to be more accurate. To test the validity of the present expression, the drying rates above which fracture occurs are determined for disk-shaped samples of pressure filtered nanocrystalline 3Y-TZP, boehmite, and silica powders. These maximum safe drying rates are used with the present expression to calculate the maximum drying stresses that can be sustained without fracture, and these stresses are compared to diametral compression-measured strengths of similar samples dried to the critical

  8. Petrophysics of low-permeability medina sandstone, northwestern Pennsylvania, Appalachian Basin

    USGS Publications Warehouse

    Castle, J.W.; Byrnes, A.P.

    1998-01-01

    Petrophysical core testing combined with geophysical log analysis of low-permeability, Lower Silurian sandstones of the Appalachian basin provides guidelines and equations for predicting gas producibility. Permeability values are predictable from the borehole logs by applying empirically derived equations based on correlation between in-situ porosity and in-situ effective gas permeability. An Archie-form equation provides reasonable accuracy of log-derived water saturations because of saturated brine salinities and low clay content in the sands. Although measured porosity and permeability average less than 6% and 0.1 mD, infrequent values as high as 18% and 1,048 mD occur. Values of effective gas permeability at irreducible water saturation (Swi) range from 60% to 99% of routine values for the highest permeability rocks to several orders of magnitude less for the lowest permeability rocks. Sandstones having porosity greater than 6% and effective gas permeability greater than 0.01 mD exhibit Swi less than 20%. With decreasing porosity, Swi sharply increases to values near 40% at 3 porosity%. Analysis of cumulative storage and flow capacity indicates zones with porosity greater than 6% generally contain over 90% of flow capacity and hold a major portion of storage capacity. For rocks with Swi < 20%, gas relative permeabilities exceed 45%. Gas relative permeability and hydrocarbon volume decrease rapidly with increasing Swi as porosity drops below 6%. At Swi above 40%, gas relative permeabilities are less than approximately 10%.

  9. Experimental Investigation on Mechanical Behavior and Permeability Evolution of a Porous Limestone Under Compression

    NASA Astrophysics Data System (ADS)

    Han, B.; Xie, S. Y.; Shao, J. F.

    2016-09-01

    This paper presents an experimental investigation on the mechanical behavior and permeability evolution of a typical porous limestone, the Anstrude limestone. Hydrostatic and triaxial compression tests are first performed under drained condition to study the basic mechanical behavior of the porous rock. Permeability measurement under both hydrostatic and triaxial compression is carried out for investigating effects of stress state on the permeability evolution along the axial direction of sample. The obtained results allow to identifying two basic plastic deformation mechanisms, the plastic shearing and pore collapse, and their effects on the permeability evolution. Under low confining pressures, the permeability diminution in the elastic phase is controlled by deviatoric stress. After the onset of plastic shearing, the deviatoric stress induces a plastic volumetric dilatation and a permeability increase. When the deviatoric stress reaches the peak strength or after the onset of shear bands, the permeability slightly decreases. Under high confining pressures, the deviatoric stress also induces a permeability diminution before the onset of plastic pore collapse. After the onset of pore collapse, the deviatoric stress leads to a plastic volumetric compaction and permeability decrease. When the deviatoric stress reaches the onset of plastic shearing, the two plastic mechanisms are in competition, the permeability continuously decreases but with a reduced rate. Finally, after the compaction-dilatation transition, the plastic shearing dominates the deformation process while the pore collapse still controls the permeability evolution.

  10. Effect of common excipients on Caco-2 transport of low-permeability drugs.

    PubMed

    Rege, B D; Yu, L X; Hussain, A S; Polli, J E

    2001-11-01

    The Biopharmaceutics Classification System (BCS) allows waivers of in vivo bioequivalence for rapidly dissolving immediate-release (IR) formulations of drugs with high solubility and high permeability. One potential issue in possibly extending BCS biowaivers to low-permeability drugs is the potential for excipients to modulate the intestinal permeability of the drug. The objective of this work was to evaluate the effect of nine individual excipients on the Caco-2 permeability of seven low-permeable compounds that differ in their physiochemical properties. Generally, most excipients had no influence on drug permeability. With the exception of sodium lauryl sulfate, no excipient affected Caco-2 monolayer integrity. Sodium lauryl sulfate moderately increased the permeability of almost all the drugs. Tween 80 significantly increased the apical-to-basolateral direction permeability of furosemide, cimetidine, and hydrochlorothiazide, presumably by inhibiting their active efflux, without affecting mannitol permeability. Additionally, docusate sodium moderately increased cimetidine permeability. Other excipients did not have significant effect on the permeability of these three drugs. Further work is needed to interpret the in vivo consequences of these observations from cell culture.

  11. Permeability of latex and polyvinyl chloride gloves to 20 antineoplastic drugs.

    PubMed

    Laidlaw, J L; Connor, T H; Theiss, J C; Anderson, R W; Matney, T S

    1984-12-01

    Permeability of latex and polyvinyl chloride (PVC) gloves to 20 injectable antineoplastic drugs was studied. Four types of gloves were evaluated: latex surgical gloves, latex examination gloves, and PVC gloves in two thicknesses. Each glove material was exposed to each drug for 90 minutes, and permeation was tested using a mutagenicity assay. Individual fingertips of thin PVC gloves and latex surgical gloves were tested for permeability at five time points (2-30 minutes) using a doxorubicin coloration assay. All drugs permeated the thin PVC gloves. Latex surgical gloves were definitely permeable to two drugs (carmustine and thiotepa) and exhibited borderline permeability to mechlorethamine hydrochloride. The thick PVC gloves were definitely permeable to four drugs (carmustine, thiotepa, mechlorethamine hydrochloride, and daunorubicin hydrochloride) and exhibited borderline permeability to two drugs (doxorubicin and mercaptopurine). The latex examination gloves were permeable to carmustine, thiotepa, mechlorethamine hydrochloride, and cyclophosphamide. Doxorubicin permeation of individual fingertips of thin PVC gloves varied in time and amount. Doxorubicin did not permeate the latex surgical glove material, but testing with thiotepa showed that individual fingertips of this material also varied in permeability. Glove thickness was a major determinant of permeability; latex surgical gloves were the least permeable and thin PVC gloves the most permeable to the antineoplastic drugs tested. Within individual gloves and glove types, time and amount of permeation were not uniform. PMID:6440436

  12. Permeability of latex and polyvinyl chloride gloves to 20 antineoplastic drugs.

    PubMed

    Laidlaw, J L; Connor, T H; Theiss, J C; Anderson, R W; Matney, T S

    1984-12-01

    Permeability of latex and polyvinyl chloride (PVC) gloves to 20 injectable antineoplastic drugs was studied. Four types of gloves were evaluated: latex surgical gloves, latex examination gloves, and PVC gloves in two thicknesses. Each glove material was exposed to each drug for 90 minutes, and permeation was tested using a mutagenicity assay. Individual fingertips of thin PVC gloves and latex surgical gloves were tested for permeability at five time points (2-30 minutes) using a doxorubicin coloration assay. All drugs permeated the thin PVC gloves. Latex surgical gloves were definitely permeable to two drugs (carmustine and thiotepa) and exhibited borderline permeability to mechlorethamine hydrochloride. The thick PVC gloves were definitely permeable to four drugs (carmustine, thiotepa, mechlorethamine hydrochloride, and daunorubicin hydrochloride) and exhibited borderline permeability to two drugs (doxorubicin and mercaptopurine). The latex examination gloves were permeable to carmustine, thiotepa, mechlorethamine hydrochloride, and cyclophosphamide. Doxorubicin permeation of individual fingertips of thin PVC gloves varied in time and amount. Doxorubicin did not permeate the latex surgical glove material, but testing with thiotepa showed that individual fingertips of this material also varied in permeability. Glove thickness was a major determinant of permeability; latex surgical gloves were the least permeable and thin PVC gloves the most permeable to the antineoplastic drugs tested. Within individual gloves and glove types, time and amount of permeation were not uniform.

  13. Co-Regulation and Interdependence of the Mammalian Epidermal Permeability and Antimicrobial Barriers

    PubMed Central

    Aberg, Karin M.; Man, Mao-Qiang; Gallo, Richard L.; Ganz, Tomas; Crumrine, Debra; Brown, Barbara E.; Choi, Eung-Ho; Kim, Dong-Kun; Schröder, Jens M.; Feingold, Kenneth R.; Elias, Peter M.

    2009-01-01

    Human epidermis elaborates two small cationic, highly hydrophobic antimicrobial peptides (AMP), β-defensin 2 (hBD2), and the carboxypeptide cleavage product of human cathelicidin (hCAP18), LL-37, which are co-packaged along with lipids within epidermal lamellar bodies (LBs) before their secretion. Because of their colocalization, we hypothesized that AMP and barrier lipid production could be coregulated by altered permeability barrier requirements. mRNA and immunostainable protein levels for mBD3 and cathelin-related antimicrobial peptide (CRAMP) (murine homologues of hBD2 and LL-37, respectively) increase 1–8 hours after acute permeability barrier disruption and normalize by 24 hours, kinetics that mirror the lipid metabolic response to permeability barrier disruption. Artificial permeability barrier restoration, which inhibits the lipid-synthetic response leading to barrier recovery, blocks the increase in AMP mRNA/protein expression, further evidence that AMP expression is linked to permeability barrier function. Conversely, LB-derived AMPs are also important for permeability barrier homeostasis. Despite an apparent increase in mBD3 protein, CRAMP−/− mice delayed permeability barrier recovery, attributable to defective LB contents and abnormalities in the structure of the lamellar membranes that regulate permeability barrier function. These studies demonstrate that (1) the permeability and antimicrobial barriers are coordinately regulated by permeability barrier requirements and (2) CRAMP is required for permeability barrier homeostasis. PMID:17943185

  14. Predicting chemically-induced skin reactions. Part II: QSAR models of skin permeability and the relationships between skin permeability and skin sensitization

    PubMed Central

    Alves, Vinicius M.; Muratov, Eugene; Fourches, Denis; Strickland, Judy; Kleinstreuer, Nicole; Andrade, Carolina H.; Tropsha, Alexander

    2015-01-01

    Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, we found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R2=0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q2ext = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. PMID:25560673

  15. Mincle Signaling Promotes Con A Hepatitis.

    PubMed

    Greco, Stephanie H; Torres-Hernandez, Alejandro; Kalabin, Aleksandr; Whiteman, Clint; Rokosh, Rae; Ravirala, Sushma; Ochi, Atsuo; Gutierrez, Johana; Salyana, Muhammad Atif; Mani, Vishnu R; Nagaraj, Savitha V; Deutsch, Michael; Seifert, Lena; Daley, Donnele; Barilla, Rocky; Hundeyin, Mautin; Nikifrov, Yuriy; Tejada, Karla; Gelb, Bruce E; Katz, Steven C; Miller, George

    2016-10-01

    Con A hepatitis is regarded as a T cell-mediated model of acute liver injury. Mincle is a C-type lectin receptor that is critical in the immune response to mycobacteria and fungi but does not have a well-defined role in preclinical models of non-pathogen-mediated inflammation. Because Mincle can ligate the cell death ligand SAP130, we postulated that Mincle signaling drives intrahepatic inflammation and liver injury in Con A hepatitis. Acute liver injury was assessed in the murine Con A hepatitis model using C57BL/6, Mincle(-/-), and Dectin-1(-/-) mice. The role of C/EBPβ and hypoxia-inducible factor-1α (HIF-1α) signaling was assessed using selective inhibitors. We found that Mincle was highly expressed in hepatic innate inflammatory cells and endothelial cells in both mice and humans. Furthermore, sterile Mincle ligands and Mincle signaling intermediates were increased in the murine liver in Con A hepatitis. Most significantly, Mincle deletion or blockade protected against Con A hepatitis, whereas Mincle ligation exacerbated disease. Bone marrow chimeric and adoptive transfer experiments suggested that Mincle signaling in infiltrating myeloid cells dictates disease phenotype. Conversely, signaling via other C-type lectin receptors did not alter disease course. Mechanistically, we found that Mincle blockade decreased the NF-κβ-related signaling intermediates C/EBPβ and HIF-1α, both of which are necessary in macrophage-mediated inflammatory responses. Accordingly, Mincle deletion lowered production of nitrites in Con A hepatitis and inhibition of both C/EBPβ and HIF-1α reduced the severity of liver disease. Our work implicates a novel innate immune driver of Con A hepatitis and, more broadly, suggests a potential role for Mincle in diseases governed by sterile inflammation. PMID:27559045

  16. Mincle Signaling Promotes Con A Hepatitis.

    PubMed

    Greco, Stephanie H; Torres-Hernandez, Alejandro; Kalabin, Aleksandr; Whiteman, Clint; Rokosh, Rae; Ravirala, Sushma; Ochi, Atsuo; Gutierrez, Johana; Salyana, Muhammad Atif; Mani, Vishnu R; Nagaraj, Savitha V; Deutsch, Michael; Seifert, Lena; Daley, Donnele; Barilla, Rocky; Hundeyin, Mautin; Nikifrov, Yuriy; Tejada, Karla; Gelb, Bruce E; Katz, Steven C; Miller, George

    2016-10-01

    Con A hepatitis is regarded as a T cell-mediated model of acute liver injury. Mincle is a C-type lectin receptor that is critical in the immune response to mycobacteria and fungi but does not have a well-defined role in preclinical models of non-pathogen-mediated inflammation. Because Mincle can ligate the cell death ligand SAP130, we postulated that Mincle signaling drives intrahepatic inflammation and liver injury in Con A hepatitis. Acute liver injury was assessed in the murine Con A hepatitis model using C57BL/6, Mincle(-/-), and Dectin-1(-/-) mice. The role of C/EBPβ and hypoxia-inducible factor-1α (HIF-1α) signaling was assessed using selective inhibitors. We found that Mincle was highly expressed in hepatic innate inflammatory cells and endothelial cells in both mice and humans. Furthermore, sterile Mincle ligands and Mincle signaling intermediates were increased in the murine liver in Con A hepatitis. Most significantly, Mincle deletion or blockade protected against Con A hepatitis, whereas Mincle ligation exacerbated disease. Bone marrow chimeric and adoptive transfer experiments suggested that Mincle signaling in infiltrating myeloid cells dictates disease phenotype. Conversely, signaling via other C-type lectin receptors did not alter disease course. Mechanistically, we found that Mincle blockade decreased the NF-κβ-related signaling intermediates C/EBPβ and HIF-1α, both of which are necessary in macrophage-mediated inflammatory responses. Accordingly, Mincle deletion lowered production of nitrites in Con A hepatitis and inhibition of both C/EBPβ and HIF-1α reduced the severity of liver disease. Our work implicates a novel innate immune driver of Con A hepatitis and, more broadly, suggests a potential role for Mincle in diseases governed by sterile inflammation.

  17. The effects of viscous forces on three-phase relative permeability

    SciTech Connect

    Maloney, D.R.; Mahmood, S.M.; Honarpour, M.M.

    1989-04-01

    The overall objective of Three-Phase Relative Permeability Project (BE9) is to develop guidelines for improving the accuracy of three-phase relative permeability determinations. This report summarizes previous studies and explains the progress made at NIPER on studying the effect of variations in viscous forces on three-phase relative permeabilities by changing the viscosity of both wetting and nonwetting phases. Significant changes were observed due to viscosity variations. An increase in oil viscosity reduced the relative permeability to gas; an increase in brine/(wetting-phase) viscosity reduced the relative permeability to brine. A slight increase in gas relative permeability was also observed. These observations suggest that the viscosities of both oil and water influence three-phase permeability data. During this study, data scatter was sometimes encountered which was comparable to that of published results. The causes of this scatter are outlined in this report and remedial attempts are discussed. 20 refs., 16 figs., 5 tabs.

  18. Relative Permeabilities: a pore-level model study of the capillary number dependence

    SciTech Connect

    Ferer, M.V.; Mason, G.; Bromhal, G.S.; Smith, D.H.

    2008-03-01

    Relative permeabilities are widely used by the petroleum industry in reservoir simulations of recovery strategies. In recent years, pore level modeling has been used to determine relative permeabilities at zero capillary number for a variety of more and more realistic model porous media. Unfortunately, these studies cannot address the issue of the observed capillary number dependence of the relative permeabilities. Several years ago, we presented a method for determining the relative permeabilities from pore-level modeling at general capillary number. We have used this method to determine the relative permeabilities at several capillary numbers and stable viscosity ratios. In addition, we have determined these relative permeabilities using one of the standard dynamic methods for determining relative permeabilities from core flood experiments. Our results from the two methods are compared with each other and with experimental results.

  19. Changes in permeability caused by transient stresses: field observations, experiments, and mechanisms

    USGS Publications Warehouse

    Manga, Michael; Beresnev, Igor; Brodsky, Emily E.; Elkhoury, Jean E.; Elsworth, Derek; Ingebritsen, Steve E.; Mays, David C.; Wang, Chi-yuen

    2012-01-01

    Oscillations in stress, such as those created by earthquakes, can increase permeability and fluid mobility in geologic media. In natural systems, strain amplitudes as small as 10–6 can increase discharge in streams and springs, change the water level in wells, and enhance production from petroleum reservoirs. Enhanced permeability typically recovers to prestimulated values over a period of months to years. Mechanisms that can change permeability at such small stresses include unblocking pores, either by breaking up permeability-limiting colloidal deposits or by mobilizing droplets and bubbles trapped in pores by capillary forces. The recovery time over which permeability returns to the prestimulated value is governed by the time to reblock pores, or for geochemical processes to seal pores. Monitoring permeability in geothermal systems where there is abundant seismicity, and the response of flow to local and regional earthquakes, would help test some of the proposed mechanisms and identify controls on permeability and its evolution.

  20. Greater scaffold permeability promotes growth of osteoblastic cells in a perfused bioreactor.

    PubMed

    Fan, Jie; Jia, Xiaoling; Huang, Yan; Fu, Bingmei M; Fan, Yubo

    2015-12-01

    Pore size and porosity have been widely acknowledged as important structural factors in tissue-engineered scaffolds. In fact, scaffolds with similar pore size and porosity can provide important and varied permeability due to different pore shape, interconnectivity and tortuosity. However, the effects of scaffold permeability on seeded cells remains largely unknown during tissue regeneration in vitro. In this study, we measured the Darcy permeability (K) of tri-calcium phosphate scaffolds by distributed them into three groups: Low, Medium and High. As a result, the effects of scaffold permeability on cell proliferation, cellular activity and growth in the inner pores were investigated in perfused and static cultures in vitro. Results demonstrated that higher permeable scaffolds exhibited superior performance during bone regeneration in vitro and the advantages of higher scaffold permeability were amplified in perfused culture. Based on these findings, scaffold permeability should be considered in future scaffold fabrications.

  1. The geometric mean concept for interpreting the permeability of heterogeneous geomaterials

    NASA Astrophysics Data System (ADS)

    Selvadurai, Patrick; Selvadurai, Paul

    2015-04-01

    Naturally occurring geomaterials are heterogeneous and the estimation of the effective permeability characteristics of such geomaterials presents a challenge not only in terms of the experimental procedures that should be used to ensure flow through the porous medium but also in the correct use of the theoretical concepts needed to accurately interpret the data. The general consensus is that the flow path in a test needs to be drastically reduced if steady state tests are considered as a suitable experimental technique. The disadvantage of flow path reduction is that the tested volume may not be altogether representative of the rock, particularly if it displays heterogeneity in the scale of the sample being tested. Also, if the sample is not correctly restrained, the differential pressures needed to initiate steady flow can introduce damage in the sample leading to erroneous estimates of permeability. The alternative approach is to use large enough samples that can capture the spatial heterogeneity but develop testing procedures that can test examine the steady state flow process as a problem in three-dimensional fluid flow that can capture the spatial distribution of permeability. The paper discusses theoretical and computational approaches that have been developed for the estimation of the spatial distribution of permeability in a cuboidal Indiana Limestone sample measuring 450 mm. The "Patch Permeability Test" developed in connection with the research allows the measurements of the surface permeability of the block and through kriging techniques estimate the permeability within the block sample. The research promotes the use of the "Geometric Mean" concept for the description of the effective permeability of the heterogeneous porous medium where the spatial distribution conforms to a lognormal pattern. The effectiveness of the approach is that the techniques can be applied to examine the effective permeability of heterogeneous low permeability materials such as

  2. Characterizing flow in oil reservoir rock using SPH: absolute permeability

    NASA Astrophysics Data System (ADS)

    Holmes, David W.; Williams, John R.; Tilke, Peter; Leonardi, Christopher R.

    2016-04-01

    In this paper, a three-dimensional smooth particle hydrodynamics (SPH) simulator for modeling grain scale fluid flow in porous rock is presented. The versatility of the SPH method has driven its use in increasingly complex areas of flow analysis, including flows related to permeable rock for both groundwater and petroleum reservoir research. While previous approaches to such problems using SPH have involved the use of idealized pore geometries (cylinder/sphere packs etc), in this paper we detail the characterization of flow in models with geometries taken from 3D X-ray microtomographic imaging of actual porous rock; specifically 25.12 % porosity dolomite. This particular rock type has been well characterized experimentally and described in the literature, thus providing a practical `real world' means of verification of SPH that will be key to its acceptance by industry as a viable alternative to traditional reservoir modeling tools. The true advantages of SPH are realized when adding the complexity of multiple fluid phases, however, the accuracy of SPH for single phase flow is, as yet, under developed in the literature and will be the primary focus of this paper. Flow in reservoir rock will typically occur in the range of low Reynolds numbers, making the enforcement of no-slip boundary conditions an important factor in simulation. To this end, we detail the development of a new, robust, and numerically efficient method for implementing no-slip boundary conditions in SPH that can handle the degree of complexity of boundary surfaces, characteristic of an actual permeable rock sample. A study of the effect of particle density is carried out and simulation results for absolute permeability are presented and compared to those from experimentation showing good agreement and validating the method for such applications.

  3. Pulmonary epithelial permeability in hyaline-membrane disease

    SciTech Connect

    Jefferies, A.L.; Coates, G.; O'Brodovich, H.

    1984-10-25

    Neonatal hyaline-membrane disease is complicated by pulmonary edema, yet left atrial pressures are normal. Alveolar-capillary-membrane permeability may therefore be increased. To assess pulmonary epithelial permeability, we measured the pulmonary clearance and half-life of aerosolized /sup 99m/Tc-diethylenetriamine pentacetate (/sup 99m/Tc-DTPA) on 31 occasions in 15 intubated premature infants with hyaline-membrane disease. Three infants with respiratory failure due to other diseases were studied on four occasions. All studies of infants with hyaline-membrane disease that were performed in the first 72 hours of life demonstrated a biphasic clearance curve with a rapid-phase half-life of 1.6 +/- 0.6 minutes (mean +/- S.D.). As these infants recovered, the curve became monophasic with a half-life of 56.0 +/- 32.1 minutes. Two infants remained dependent on oxygen and ventilator support and had persistent biphasic curves with a rapid-phase half-life of 1.5 +/- 0.7 minutes. All infants without hyaline-membrane disease had monophasic curves with a half-life of 65.4 +/- 33.6 minutes. Using a similar technique, we observed that newborn lambs and piglets have a monophasic pulmonary clearance of /sup 99m/Tc-DTPA (114 +/- 59 minutes in lambs and 52.5 +/- 16.3 minutes in piglets). We conclude that the lungs of neonates with hyaline-membrane disease are abnormally permeable to small solutes and that this abnormality persists in infants with subsequent chronic lung disease.

  4. Permeability of low molecular weight organics through nanofiltration membranes.

    PubMed

    Meylan, Sébastien; Hammes, Frederik; Traber, Jacqueline; Salhi, Elisabeth; von Gunten, Urs; Pronk, Wouter

    2007-09-01

    The removal of natural organic matter (NOM) using nanofiltration (NF) is increasingly becoming an option for drinking water treatment. Low molecular weight (LMW) organic compounds are nevertheless only partially retained by such membranes. Bacterial regrowth and biofilm formation in the drinking water distribution system is favoured by the presence of such compounds, which in this context are considered as the assimilable organic carbon (AOC). In this study, the question of whether NF produces microbiologically stable water was addressed. Two NF membranes (cut-off of about 300Da) were tested with different natural and synthetic water samples in a cross-flow filtration unit. NOM was characterised by liquid chromatography with organic carbon detection (LC-OCD) using a size-exclusion column in addition to specific organic acid measurements, while AOC was measured in a batch growth bioassay. Similarly to high molecular weight organic compounds like polysaccharides or humic substances that have a permeability lower than 1%, charged LMW organic compounds were efficiently retained by the NF membranes tested and showed a permeability lower than 3%. However, LMW neutrals and hydrophobic organic compounds permeate to a higher extent through the membranes and have a permeability of up to 6% and 12%, respectively. Furthermore, AOC was poorly retained by NF and the apparent AOC concentration measured in the permeated water was above the proposed limit for microbiologically stable water. This indicates that the drinking water produced by NF might be biologically unstable in the distribution system. Nevertheless, in comparison with the raw water, NF significantly reduced the AOC concentration.

  5. Mining-Induced Coal Permeability Change Under Different Mining Layouts

    NASA Astrophysics Data System (ADS)

    Zhang, Zetian; Zhang, Ru; Xie, Heping; Gao, Mingzhong; Xie, Jing

    2016-09-01

    To comprehensively understand the mining-induced coal permeability change, a series of laboratory unloading experiments are conducted based on a simplifying assumption of the actual mining-induced stress evolution processes of three typical longwall mining layouts in China, i.e., non-pillar mining (NM), top-coal caving mining (TCM) and protective coal-seam mining (PCM). A theoretical expression of the mining-induced permeability change ratio (MPCR) is derived and validated by laboratory experiments and in situ observations. The mining-induced coal permeability variation under the three typical mining layouts is quantitatively analyzed using the MPCR based on the test results. The experimental results show that the mining-induced stress evolution processes of different mining layouts do have an influence on the mechanical behavior and evolution of MPCR of coal. The coal mass in the PCM simulation has the lowest stress concentration but the highest peak MPCR (approximately 4000 %), whereas the opposite trends are observed for the coal mass under NM. The results of the coal mass under TCM fall between those for PCM and NM. The evolution of the MPCR of coal under different layouts can be divided into three sections, i.e., stable increasing section, accelerated increasing section and reducing section, but the evolution processes are slightly different for the different mining layouts. A coal bed gas intensive extraction region is recommended based on the MPCR distribution of coal seams obtained by simplifying assumptions and the laboratory testing results. The presented results are also compared with existing conventional triaxial compression test results to fully comprehend the effect of actual mining-induced stress evolution on coal property tests.

  6. The Fate of Nitrate in Intertidal Permeable Sediments

    PubMed Central

    Marchant, Hannah K.; Lavik, Gaute; Holtappels, Moritz; Kuypers, Marcel M. M.

    2014-01-01

    Coastal zones act as a sink for riverine and atmospheric nitrogen inputs and thereby buffer the open ocean from the effects of anthropogenic activity. Recently, microbial activity in sandy permeable sediments has been identified as a dominant source of N-loss in coastal zones, namely through denitrification. Some of the highest coastal denitrification rates measured so far occur within the intertidal permeable sediments of the eutrophied Wadden Sea. Still, denitrification alone can often account for only half of the substantial nitrate (NO3−) consumption. Therefore, to investigate alternative NO3− sinks such as dissimilatory nitrate reduction to ammonium (DNRA), intracellular nitrate storage by eukaryotes and isotope equilibration effects we carried out 15NO3− amendment experiments. By considering all of these sinks in combination, we could quantify the fate of the 15NO3− added to the sediment. Denitrification was the dominant nitrate sink (50–75%), while DNRA, which recycles N to the environment accounted for 10–20% of NO3− consumption. Intriguingly, we also observed that between 20 and 40% of 15NO3− added to the incubations entered an intracellular pool of NO3− and was subsequently respired when nitrate became limiting. Eukaryotes were responsible for a large proportion of intracellular nitrate storage, and it could be shown through inhibition experiments that at least a third of the stored nitrate was subsequently also respired by eukaryotes. The environmental significance of the intracellular nitrate pool was confirmed by in situ measurements which revealed that intracellular storage can accumulate nitrate at concentrations six fold higher than the surrounding porewater. This intracellular pool is so far not considered when modeling N-loss from intertidal permeable sediments; however it can act as a reservoir for nitrate during low tide. Consequently, nitrate respiration supported by intracellular nitrate storage can add an additional 20% to

  7. α-Synuclein amino terminus regulates mitochondrial membrane permeability.

    PubMed

    Shen, Jiamei; Du, Tingting; Wang, Xue; Duan, Chunli; Gao, Ge; Zhang, Jianliang; Lu, Lingling; Yang, Hui

    2014-12-01

    Parkinson's disease (PD) is a common neurodegenerative movement disorder affecting an increasing number of elderly. Various studies have shown that mitochondrial dysfunction and abnormal protein aggregation are two major contributors to the progression of PD. The N terminus of α-synuclein (α-Syn/N), which adopts an α-helical conformation upon lipid binding, is essential for membrane interaction; yet its role in mitochondria remains poorly defined. A functional characterization of the α-Syn N-terminal domain and investigation of its effect on mitochondrial membrane permeability were undertaken in this study. α-Syn/N and α-Syn/delN (amino acids 1-65 and 61-140, respectively) constructs were overexpressed in dopaminergic MN9D cells and primary cortical neurons. A decrease in cell viability was observed in cells transfected with α-Syn/N but not α-Syn/delN. In addition, an α-Syn/N-induced increase in the level of intracellular reactive oxygen species, alteration in mitochondrial morphology, and decrease in mitochondrial membrane potential were accompanied by the activation of mitochondrial permeability transition pores (mPTP). These changes were also associated with a decline in mitochondrial cardiolipin content and interaction with the voltage-dependent anion channel and adenine nucleotide translocator in the mitochondrial membrane. The activation of mPTPs and reduction in cell viability were partially reversed by bongkrekic acid, an inhibitor of adenine nucleotide translocator (ANT), suggesting that the interaction between α-Syn and ANT promoted mPTP activation and was toxic to cells. BKA treatment reduced interaction of α-Syn/N with ANT and VDAC. These results suggest that the N terminus of α-Syn is essential for the regulation of mitochondrial membrane permeability and is a likely factor in the neurodegeneration associated with PD.

  8. Demonstrations of magnetic phenomena: measuring the air permeability using tablets

    NASA Astrophysics Data System (ADS)

    Lara, V. O. M.; Amaral, D. F.; Faria, D.; Vieira, L. P.

    2014-11-01

    We use a tablet to experimentally determine the dependencies of the magnetic field (B) on the electrical current and the axial distance from a coil (z). Our data shows good precision on the inverse cubic dependence of the magnetic field on the axial distance, B ∝ z-3. We obtain the value of air permeability μair with good accuracy. We also observe the same dependence of B on z when considering a magnet instead of a coil. Although our estimates are obtained through simple data fits, we also perform a more sophisticated error analysis, confirming the result for μair.

  9. Deformation bands at andesitic stratovolcanoes and their impact on permeability

    NASA Astrophysics Data System (ADS)

    Farquharson, Jamie; Heap, Michael; Varley, Nick; Baud, Patrick

    2015-04-01

    The edifice-forming andesitic rocks at Volcán de Colima (Mexico) host a multitude of curious planar to subplanar deformation features. During a recent field campaign (May/June 2014) we collected 14 blocks from different localities around the volcano (from debris-flow tracks and parasitic dome "Volcancito"), chosen to represent the variety of observable features. First order observations suggest that, while some of these bands (usually distinguished by a difference in colour) are essentially planar, others have undergone various degrees of post-formation viscous deformation. In the most extreme cases, the bands have been twisted and stretched to the point were they are preserved as wispy lenses. Scanning electron microscopy has shown that the different bands are characterised by very different microstructural textures, suggesting fundamentally different mechanisms of genesis. For example, some features are bands of higher porosity than the surrounding host rock in which the groundmass appears to have been removed by the movement of hydrothermal fluids along pre-existing cracks or in thicker (1-2 cm) zones now characterised by pervasive microporous textures. Some bands, observable because macropores (1 mm) have been filled by secondary mineralisation, contain a lower porosity than the adjacent host rock. We also find evidence of variably efficient bubble elongation, possibly indicating "frozen" decompression events within pumiceous samples. We cored cylindrical samples from the blocks to contain bands either parallel or perpendicular to the fluid (gas) flow direction in our laboratory permeameter setup (other samples were cored to contain no bands; i.e., the host rock). Our permeability measurements show that some features act as conduits while others serve as barriers to fluid flow. The importance of such features is emphasised by their large impact on permeability; changes in permeability can be as high as two orders of magnitude for certain bands. These data do

  10. [Effects of colchicine and of emetine on capillary permeability].

    PubMed

    Toscano Rico, J; Gião T Rico, J M; Zambelli de Almeida, M T; Cravo, A C; Costa Ferreira, J M

    1975-01-01

    Colchicine and emetine administered locally in the hind paw of the rats increased markedly the capillar permeability. The action may be strongly inhibited by methysergide (0.2 mug). Mepyramine (0.5 mug) is not so active and indomethacine (1 mg/kg per os), even less. As some prostaglandines release serotonine and histamine (8) it is possible that some liberation of these mediators may be attribuable to a previous release of prostaglandines, but the experiments suggest also the possibility of a direct and concomitant release of those two mediators by the alkaloids assayed.

  11. Composite medium with simultaneously negative permeability and permittivity

    PubMed

    Smith; Padilla; Vier; Nemat-Nasser; Schultz

    2000-05-01

    We demonstrate a composite medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous wires, that exhibits a frequency region in the microwave regime with simultaneously negative values of effective permeability &mgr;(eff)(omega) and permittivity varepsilon(eff)(omega). This structure forms a "left-handed" medium, for which it has been predicted that such phenomena as the Doppler effect, Cherenkov radiation, and even Snell's law are inverted. It is now possible through microwave experiments to test for these effects using this new metamaterial. PMID:10990641

  12. Composite Medium with Simultaneously Negative Permeability and Permittivity

    SciTech Connect

    Smith, D. R.; Padilla, Willie J.; Vier, D. C.; Nemat-Nasser, S. C.; Schultz, S.

    2000-05-01

    We demonstrate a composite medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous wires, that exhibits a frequency region in the microwave regime with simultaneously negative values of effective permeability {mu}{sub eff}({omega}) and permittivity {epsilon}{sub eff}({omega}) . This structure forms a ''left-handed'' medium, for which it has been predicted that such phenomena as the Doppler effect, Cherenkov radiation, and even Snell's law are inverted. It is now possible through microwave experiments to test for these effects using this new metamaterial. (c) 2000 The American Physical Society.

  13. Em Response of a Conductive, Permeable Spherical Shell

    2005-10-24

    This code calculates the spectral response of conductive, permeable, shell in a conductive whole space using a closed form solution. The source is either a uniform field (approximately valid when the size of the sphere is small compared to the distance to the source) or the field of dipole (and by superposition, the field of a finite loop). The code is particularly useful in showing that the typical UXO (usually shells), the response is significantlymore » different at intermediate to late times compared to solids of the same materials.« less

  14. Fluctuations of Permeable Interfaces in Water-in-Water Emulsions

    NASA Astrophysics Data System (ADS)

    Sagis, Leonard M. C.

    2007-02-01

    The fluctuations of highly permeable interfaces, encountered in phase-separated biopolymer solutions, liposomes, polymersomes, or colloidosomes, are investigated. An expression for the power spectrum of the height correlation function is derived for a multicomponent system, incorporating the effects of mass transfer across the interface, using nonequilibrium thermodynamics. We also derive an expression for the relaxation time of the height correlation function, and calculate the relaxation time for a phase-separated gelatin-dextran-water system. Comparing our expression with the expression for an impermeable interface shows that mass transfer has a significant impact on the relaxation time of the interface.

  15. Liquid Spills on Permeable Soil Surfaces: Experimental Confirmations

    SciTech Connect

    Simmons, Carver S.; Keller, Jason M.

    2005-09-29

    Predictive tools for assessing the quantity of a spill on a soil from the observed spreading area could contribute to improving remediation when it is necessary. On a permeable soil, the visible spill area only hints about the amount of liquid that might reside below the surface. An understanding of the physical phenomena involved with spill propagation on a soil surface is key to assessing the liquid amount possibly present beneath the surface. The objective of this study is an improved prediction capability for spill behavior.

  16. Glycyrrhetinic acid-induced permeability transition in rat liver mitochondria.

    PubMed

    Salvi, Mauro; Fiore, Cristina; Armanini, Decio; Toninello, Antonio

    2003-12-15

    Glycyrrhetinic acid, a hydrolysis product of one of the main constituents of licorice, the triterpene glycoside of glycyrrhizic acid, when added to rat liver mitochondria at micromolar concentrations induces swelling, loss of membrane potential, pyridine nucleotide oxidation, and release of cytochrome c and apoptosis inducing factor. These changes are Ca(2+) dependent and are prevented by cyclosporin A, bongkrekic acid, and N-ethylmaleimide. All these observations indicate that glycyrrhetinic acid is a potent inducer of mitochondrial permeability transition and can trigger the pro-apoptotic pathway. PMID:14637195

  17. Development of high permeability nanocrystalline permalloy by electrodeposition

    NASA Astrophysics Data System (ADS)

    Seet, H. L.; Li, X. P.; Zhao, Z. J.; Kong, Y. K.; Zheng, H. M.; Ng, W. C.

    2005-05-01

    In this study, for developing microsensors for weak magnetic field, methods for developing high permeability nanocrystalline permalloy by electrodeposition and the relationship between the grain size and magnetic properties of the nanocrystalline permalloy are investigated. By dc plating with and without saccharin added and pulse plating with saccharin added, permalloy samples of grain sizes from 52 nm to 11 nm are obtained. The coercivity and magnetoimpedance (MI) ratio of the samples are tested against the grain size variation. Results show that the coercivity decreases rapidly and MI ratio increases greatly with grain size decrease from 52 nm to 11 nm.

  18. Development of high permeability nanocrystalline permalloy by electrodeposition

    SciTech Connect

    Seet, H.; Li, X.P.; Zhao, Z.J.; Kong, Y.K.; Zheng, H.M.; Ng, W.C.

    2005-05-15

    In this study, for developing microsensors for weak magnetic field, methods for developing high permeability nanocrystalline permalloy by electrodeposition and the relationship between the grain size and magnetic properties of the nanocrystalline permalloy are investigated. By dc plating with and without saccharin added and pulse plating with saccharin added, permalloy samples of grain sizes from 52 nm to 11 nm are obtained. The coercivity and magnetoimpedance (MI) ratio of the samples are tested against the grain size variation. Results show that the coercivity decreases rapidly and MI ratio increases greatly with grain size decrease from 52 nm to 11 nm.

  19. Method for temporarily reducing permeability of subterranean formations

    SciTech Connect

    Williamson, C.D.; Allenson, S.J.; Gabel, R.K.

    1991-04-23

    This patent describes an improved method for hydraulic fracturing of subterranean formations penetrated by a wellbore. It comprises dispersing in a fracturing media a fluid loss additive to form an improved fracturing media, the fluid loss additive comprising a blend of two or more modified starches; and pumping the improved fracturing media into a wellbore at a pressure sufficient to lift the overburden and fracture the formation, whereby a filter cake with low permeability will be rapidly formed, the filter cake being readily degraded after completion of the fracturing process.

  20. Rhubarb Antagonizes Matrix Metalloproteinase-9-induced Vascular Endothelial Permeability

    PubMed Central

    Cui, Yun-Liang; Zhang, Sheng; Tian, Zhao-Tao; Lin, Zhao-Fen; Chen, De-Chang

    2016-01-01

    Background: Intact endothelial structure and function are critical for maintaining microcirculatory homeostasis. Dysfunction of the latter is an underlying cause of various organ pathologies. In a previous study, we showed that rhubarb, a traditional Chinese medicine, protected intestinal mucosal microvascular endothelial cells in rats with metastasizing septicemia. In this study, we investigated the effects and mechanisms of rhubarb on matrix metalloproteinase-9 (MMP9)-induced vascular endothelial (VE) permeability. Methods: Rhubarb monomers were extracted and purified by a series of chromatography approaches. The identity of these monomers was analyzed by hydrogen-1 nuclear magnetic resonance (NMR), carbon-13 NMR, and distortionless enhancement by polarization transfer magnetic resonance spectroscopy. We established a human umbilical vein endothelial cell (HUVEC) monolayer on a Transwell insert. We measured the HUVEC permeability, proliferation, and the secretion of VE-cadherin into culture medium using fluorescein isothiocyanate-dextran assay, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay, and enzyme-linked immunosorbent assay, respectively, in response to treatment with MMP9 and/or rhubarb monomers. Results: A total of 21 rhubarb monomers were extracted and identified. MMP9 significantly increased the permeability of the HUVEC monolayer, which was significantly reduced by five individual rhubarb monomer (emodin, 3,8-dihydroxy-1-methyl-anthraquinone-2-carboxylic acid, 1-O-caffeoyl-2-(4-hydroxyl-O-cinnamoyl)-β-D-glucose, daucosterol linoleate, and rhein) or a combination of all five monomers (1 μmol/L for each monomer). Mechanistically, the five-monomer mixture at 1 μmol/L promoted HUVEC proliferation. In addition, MMP9 stimulated the secretion of VE-cadherin into the culture medium, which was significantly inhibited by the five-monomer mixture. Conclusions: The rhubarb mixture of emodin, 3,8-dihydroxy-1-methyl-anthraquinone-2